The Ductile Iron Society Visits Neenah Foundry at 115th Technical and Operating Meeting

Transcription

1 To Promote the production and application of ductile iron castings Issue 3, 2001 The Ductile Iron Society Visits Neenah Foundry at 115th Technical and Operating Meeting Photos of Meeting Attendees More photos of Neenah Foundry FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

2 To Promote the production and application of ductile iron castings Issue 3, 2001 Cover, page 1, page 2, page 3 Neenah's pattern shop provides industry leading use of synthetic materials and computer technology for production tooling. Complex cores, beyond the range of most foundries, are routine in Neenah's daily production. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Before quoting your job, we carefully listen to your people to be certain we completely understand your design, application, and specifications. Every To ensure metallurgic uniformity, Neenah operates question is asked, every detail is considered, every some of the longest cooling lines in the industry part of the process is planned before your casting is quoted. Variables become constants prior to production of your castings. View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

3 he Ductile Iron News - Neenah Pictures To Promote the production and application of ductile iron castings Issue 3, 2001 Neenah combines advanced technology with traditional craftsmanship to produce castings that meet or exceed your expectations. Cover, page 1, page 2, page 3 Minimizing process variation and maximizing process efficiency receive critical attention at Neenah. Customer needs define and drive our manufacturing process, resulting in comprehensive, full service capabilities. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Neenah enhances Disamatic technology with unique coresetting capabilities that provide castings with a competitive advantage. At Neenah, excellence in both product reliability and customer service is the number one priority. View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

4 he Ductile Iron News - Neenah Pictures To Promote the production and application of ductile iron castings Issue 3, 2001 Cover, page 1, page 2, page 3 Neenah Foundry...people, processes, and capabilities uniquely qualified to meet your needs. Neenah Foundry Assessment Information Melt Capability Located 100 miles Northwest of Milwaukee, Wisconsin Producing Gray (class 30 and 35) and Ductile Iron castings (D4018, D4512, D5506 and D7003) Annual shipping capacity in excell of 150,000 tons Fully facilitized pattern shop Transportation fleet Melt: Three 72" Refractory line water-cooled Hot Blast cupolas with O 2 injection (60 ton/hour) FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Duplex: Three 60 ton Vertical Channel furnaces Pour: Three 10 ton and One 6 ton Jünker horizontal channel (pressurized) stopper rod furnaces with instream inoculation (Note: pouring systems have dual inoculators) Core Two CB-30 horizontal isocure core machines 45" x 40" platen 350 lbs. maximum core weithg Two 18 liter Peterle vertical isocure core machines 31.5" x 23.8" platen 100 lbx. maximum core weight Two 12 liter Peterle vertical isocure core machines 27.5" x 23.8" platen 70 lbs. maximum core weight Two 12 liter Peterle vertical shell core machines 19.6" x 17.9" platen 35 lbs. maximum core weight Molding One 2013 Mark 4 Disamatic molding machine Mold size is 21" x 25.6" 100 lbs. maximum pour weight

5 Up to 410 molds/hour Two 2070 Type B Disamatic molding machines Mold size is 31.5" x 37.4" 275 lbs. maximum pour weight automatic pattern changing system automatic core setting up to 260 molds/hour per machine One BMD air impulse molding line. 44" x 50" flasks with 10" cope and 16" drag heights 500 lbs. maximum pour weight Other Fully facilitized process control labs, paint line, complete casting engineering services Brooks Avenue Box 729 Neenah, WE Phone: Fax: View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

6 The Ductile Iron News - Operating Committee Meeting To Promote the production and application of ductile iron castings Issue 3, 2001 DIS Operating Committee Meeting Wednesday, October 3, 2001 Oshkosh, Wisconsin Minutes The newly formed Operating Committee met for the first time. Thirty-six people representing nine Foundry members and 17 Associate Members were in attendance. We opened with "round robin" introductions and with each person in attendance discussing, briefly, the markets and business environment from their perspective. In general, the comments were that business was slow, however some members reported "pockets of prosperity". In general, slow times have resulted in businesses improving their performance and engineers looking for new solutions. This has resulted in an increase in quoting activity and requests for products and services related to improved product performance or reduced manufacturing costs. After introductions, DIS President, Denny Dotson introduced the new committee format and the structure that had been first discussed at the Waterloo, Ontario meeting last spring. It was the goal of that steering committee to establish a committee structure that more effectively "tapped" the talents of the DIS membership and one that would improve the effectiveness of the organization. At an ad hoc steering committee meeting in Waterloo, four subcommittees were defined to combine and replace the existing committee structure. They are as follows: -Marketing Committee / DIMG: Paul Gerhardt, Chmn. -Programs and Publications Committee: Jim Wood, Chmn. -Member Services Committee: Tim Brown, Chmn. -College & University Relations: John Keough, Chmn. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, The DIS Board is dealing with any necessary modifications in DIS policy related to these changes. Those policy issues are outside the scope of these newly formed committees. Denny Dotson asked the Operating Committee members present to choose a subcommittee that best fits their skills. Then he charged each subcommittee with the responsibility of establishing a Mission Statement and some measurables related to the execution of that Mission. The Operating Committee then broke out into the newly established committees. The organization and outcomes of that subcommittee work follow. Ductile Iron Marketing Committee Gene Muratore* Jerry Wurtsmith Rick Gundlach Jim Stevenson John Wagner Bob O'Rourke Terry Lusk John Hendrix Ron Aufderheide Jim Mullins *Committee Chairman, Paul Gerhardt was absent. In his absence Gene Muratore filled the role of acting Chairman. Mission Statement: To disseminate information about the attributes of Ductile Iron to the metal forming industries by all appropriate means. This includes, but is not limited to: 1. Paid and non-paid press releases and advertising of the DIMG technical booklets. file:///c /WEBSHARE/062013/magazine/2001_3/opcommittee.htm[6/19/ :21:30 AM]

7 The Ductile Iron News - Operating Committee Meeting 2. Use of the DIS website. 3. "Cast It" and "Cast It in Ductile Iron" on video and compact disk. 4. Exhibiting at trade shows. 5. Seminars for design, materials and manufacturing engineers. Goals: Increase awareness of the attributes of Ductile Iron (castings) amongst design engineers, material specifiers, and component purchasers/manufacturers, by expanding on the efforts of the DIMG, through additional funding from the DIS. Current Activities: The following describe the scope of the activities of the DIMG. 1. Ongoing press releases for DIMG literature 2. Preparation of a press release for the "Cast It" video conversion to CD. This release will go to trade magazines, not on the website, as the original pressing may be insufficient vs. the volume of requests on the internet. 3. All DIMG literature is now uploaded to the DIS website and is fully downloadable. 4. Negotiations are underway with AFS to share space at the SAE show in Detroit in March 2002 and at the ConAgg/ConExpo/IFPE/SAE Off Highway show in Las Vegas in March Discussion items: 1. Wells Durabar has secured space at the Las Vegas show and has offered the DIMC an opportunity to share the space. Final details will be worked out with Bob O'Rourke. Investigating the possibility of a "live" computer link in the booth for access to the DIS website. 2. The DIMC will be responsible for programs/speakers at these venues. 3. Very few members of the committee have viewed the "Cast It" video. One copy of the video was circulated to all committee members from the Rio Tinto office with an address list of committee members for mailing. 4. Discussions were held on how to get more visitors to the website. One possible solution is to purchase a list of names and make a mass to the list. The title of the must be attractive in order to avoid instantaneous deletion of the by wary engineers. 5. The AFS has announced that there will be no shared space at the SAE show in Detroit. The committee must evaluate the benefit of space specifically for the DIMC. This would incur and additional expense that is not currently in the DIMG budget. 6. The feasibility of a DIMC Bulletin Board on the website was discussed. It was uncovered that the DIS website will unveil a Contact Us section within 60 days that could serve the same purpose of a bulletin board. This can be a platform for queries from design engineers regarding Ductile Iron. 7. No discussion of the DIMG budget was held, although the numbers are as follows: Revenue: DIMG $10,000 RTIT $10,000 Total $20,000 Expense Budget: 02 SAE Show w/afs $ 1,500 file:///c /WEBSHARE/062013/magazine/2001_3/opcommittee.htm[6/19/ :21:30 AM]

8 The Ductile Iron News - Operating Committee Meeting Postage etc. $ 2,500 Advertising $15,000 Video to CD $ 3,000 Total $22,000 Programs and Publications Committee Jim Wood-Chmn. Gene Muratore David Sparkman Steve Sauer Al Alagarsamy Tony Thoma Kathy Hayrynen Cory Ashburn Mission Statement: To obtain the highest quality of speakers to communicate the newest technology of Ductile Iron and related processes. The can be accomplished through speakers at each T&O meeting and various publications of the Ductile Iron Society. Goals and Objectives: 1. Establish speak guidelines (by July 2002) 2. Address the issue of commercialism (by June 2002) 3. Review presentations in advance a. Slides / PowerPoint b. Full written report c. 200 word abstracts 4. Producers subjects of interest (members to provide to Chmn. Oct 01) 5. Review speakers package for adequacy (by Oct 2002) 6. Any changes in the program chairmen (by July 2002) 7. Promote DIS Research Committee presentations (by Oct 2002) 8. Speaker gifts (by Oct 2002) 9. Keith Millis Symposium arrangements (Oct 2003) 10. ADI Conference (Fall 2002) 11. Articles and abstracts on DIS website (by June 2002) 12. $400 payment for speaker abstracts of presentations (Oct 2001) Member Services Committee Dennis Dotson* Hugh Kind Alan Anderson Barry Snyder *Chairman Tim Brown was absent and Denny Dotson served as Acting Chairman Mission Statement: To make DIS valuable to existing and potential customers. Goals: 1. Establish a list of 50 qualified potential new members, 2. Bring three potential members to each meeting 3. Review participation at DIS events and in services (compared to past years). 4. Conduct a survey of membership on benefits of DIS College and University Relations Committee John Keough-Chmn. Christof Heisser George DiSylvestro file:///c /WEBSHARE/062013/magazine/2001_3/opcommittee.htm[6/19/ :21:30 AM]

9 The Ductile Iron News - Operating Committee Meeting Mike Mroczek Kris Kitchen Julie Fitzpatrick James Mikoda Dan Korpi Jim Csonka Mission Statement: To expose the maximum number of young adults possible to Ductile Iron technology as it relates to its: Design Application Manufacture Research Career Opportunities Action Items (Oct May 2002) 1. Provide a hard copy of "Ductile Iron Data for Design Engineers" to all students attending the FEF CIC conference and those attending the AFS Cast Expo. a. Keough to acquire the books b. Mroczek to prepare the DIS stickers c. Fitzpatrick to draft a letter to accompany the books. 2. Invite local students to next DIS meeting. a. Csonka / Keough View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

10 he Ductile Iron News - Photos of Attendees To Promote the production and application of ductile iron castings Issue 3, 2001 Photos of Attendees at the 115th T&O Meeting - Neenah Foundry Andy Adams with Gene Muratore Mark Eckert with Gene Muratore Click on any photo to see enlargement John Keough with Gene Muratore Cristof Heisser with Gene Muratore Eli David with Gene Muratore Ron Aufderheide with Gene Muratore Chuck and Mary Jo Kurtti Frank and Barbara Headington FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, John Andrews Bill Barrett Denny Dotson Gene Muratore Laura Strohmayer View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

11 he Ductile Iron News - Simulation of Microstructure and Mechanical Properties in Ductile Iron To Promote the production and application of ductile iron castings Issue 3, 2001 Simulation of Microstructure and Mechanical Properties in Ductile Iron Abstract: Since the introduction of "Solidification Simulation" in the foundry industry, which happened almost 20 years ago, only a few of the available simulation tools have matured into true "Casting Process Simulation" tools. The specific solidification behavior of ductile iron is very complicated, hence, challenging to model. This paper will cover the mechanisms of the solidification and cooling of ductile iron that are considered in one of the leading casting process simulation tools. One example shows the elimination of risers on an actual ductile iron casting to show the financial savings in the foundry and the difference between a simple solidification simulation and a highly sophisticated casting process and micromodeling tool. A comparison of actual microstructure measured in test castings and simulated microstructures are shown, as well. Development of Casting Process Simulation for Iron Castings: FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Fig. 1: Timeline of simulation tool development Initially the term "Solidification Simulation" meant exactly that. Tools used a homogeneous temperature distribution (one temperature) throughout the entire casting as starting condition. Very often just single values for thermophysical properties, i.e. density, conductivity, specific heat capacity were considered by the codes, not temperature dependent values. Some tools didn't even consider the mold material surrounding the casting. Those tools were used to predict hotspots in castings. These tools considered neither the influence of the temperature loss of the melt during the filling process, nor material transport phenomena. The use of these tools lead to many over-risered castings especially in iron foundries. The solidification of gray and ductile iron is characterized by the interaction of multiple components and their volume changes. One of the most important factors is the graphite expansion versus the shrinkage of the metal matrix during the iron solidification. Both are influenced tremendously by the metallurgy, i.e. the composition, inoculation, graphite precipitation, and the melt treatment. Not to be forgotten should be the influence of the mold material with regard to mold stability (mold wall movement) and moisture content. The need to consider all of these factors leads to the necessity to micro-model the creation of the microstructure during the solidification (Figure 1). Actually, it is beneficial to consider certain effects, like fading of inoculants and pre-solidifying sections of the casting, during the filling process. In many cases sound iron castings can be produced without risers. But only highly sophisticated casting

12 process simulation tools can be used to simulate these kind of casting successfully. The modeling of the microstructure during the solidification process allows the tool to continue simulating the cooling process of the casting all the way down to room temperature. Hence, a prediction of the microstructure at room temperature can be made in conjunction with a prediction of mechanical properties. This functionality becomes more and more important for the cooperation between the iron foundries with casting designers, especially in combination with the prediction of residual stresses and distortion in castings. Example 1: Ductile Iron Ring Casting The foundry producing the 5600-lbs. ductile iron (Grade ) ring casting had problems with under riser shrink. No matter how many risers they used, always shrinkage porosity appeared below the risers (Figures 2 through 4). Fig. 2: Ring casting with removed risers Fig. 3: Detail view of broken off riser connection Fig. 4: Picture of shrinkage under riser

13 The casting is poured into a very rigid chemically bonded mold, which would allow the foundry to consider a riserless gating design. However, the use of a simple "Solidification Simulation" tool predicted a ring shaped shrink inside the casting (Figure 5). Fig. 5: Ring-shaped shrinkage predicted by "Solidification Simulation" At that time the yield of the casting was 77% and the scrape rate was 50%. It was decided to use a casting process simulation tool (MAGMASOFT) to reproduce the present under riser shrink and verify the appropriate process setup in the casting process simulation. The initial casting process simulation considering the filling process, the metallurgy and melt treatment, as well as, the appropriate mold stability and properties reproduced the present under-riser shrink (Figure 6) Fig. 6: Simulated under-riser shrink Fig. 7: Simulated under-riser shrink second run was conducted using a riserless design. The results show a casting with only minor defects on the surface, but none inside the casting (Figures 8 and 9).

14 Fig. 8: Minor surface shrink on riserless design Fig. 9: No shrink inside casting with riserless design After these simulation runs the foundry started producing defect-free castings without risers. The minor surface shrink, if present, is of no concern because it gets removed by the machining. The financial impact of this change is significant (Figure 10). # of Castings lbs. $/lbs. $ Yield Savings $0.35 $ 6,720 Cost of Sleeves 40 8 $8.00 $ 2,560 Riser Removal 40 8 $5.00 $ 1,600 Production Savings $10,880 Scrap Casting $0.65 $72,800 Annual Savings $83,680 Fig. 10: Savings of more than US$ 80, per year have been realized Not only are the costs reduced for each new casting due to yield improvement, elimination of exothermic sleeves and riser removal costs, but the overall scrap rate has been reduced to 4%, too. This eliminated the need to produce additional 20 castings per year to deliver 40 sound castings. Using "Casting Process Simulation "instead of" Solidification Simulation saved more than US$ 80, This example proves that it is essential to consider the entire casting process and micro-model the creation of the ductile iron microstructure to get an accurate shrinkage prediction. Example 2: Ductile Iron Ring Casting

15 A ductile iron test casting was poured as part of the Thin Wall Iron Group (TWIG) research program. The part included interconnected plates (stair step casting) and separate plates with different wall thickness ranging from 2 to 6 mm in thickness (Figure 11). Fig. 11: Test Casting Image analysis was used to evaluate the microstructure in a center plane of the stepped area and the separate plates. A casting process simulation was conducted considering the entire casting process, the metallurgy and the cooling process including phase changes to predict the as-cast microstructure at room temperature. The comparison of the measured and the simulated values for nodule-count, ferrite and carbide distribution show very close matches (Figures 12 through 16). Besides the confirmation of the wall-thickness dependency of the microstructure it was also confirmed how important it is to consider the temperature loss of the melt during the filling process and the resulting preconditioning of the sand mold due to the filling. Differences in wall-thickness and the resulting differences in local cooling rates, alone cannot explain the measured distributions in the stepped area of the casting. Fig. 12: Comparison of nodule-count distribution in step plate

16 Fig. 13: Comparison of ferrite distribution in step plate Fig. 14: Comparison of carbide distribution in step plate Fig. 15: Comparison of nodule-count distribution in separate plate Fig. 16: Comparison of ferrite distribution in separate plate Example 3: Mechanical Property Prediction in Ductile Iron Crankshaft In the frame of a casting engineering project the casting process of a ductile iron crankshaft was evaluated with regard to casting defects, microstructure and as-cast mechanical properties. After implementing the process conditions present in this particular foundry the simulation showed a close match to the microstructure and mechanical properties found in the castings (Figure 17). The final simulation lead to an optimized gating system, which reduced the filling time by 45% and eliminated inclusion problems, found previously in the castings. The riser size was reduced, improving the yield of the casting. A significant cost reduction was achieved by the elimination of chills, after the simulation showed that a defect-free casting with sufficient mechanical properties could be produced without them.

17 Fig. 17: Mechanical property distribution in ductile iron crankshaft View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440)

18 The Ductile Iron News - Offsetting Macro-shrinkage in Ductile Iron To Promote the production and application of ductile iron castings Issue 3, 2001 Offsetting Macro-Shrinkage in Ductile Iron What Thermal Analysis Shows By David Sparkman May 30, 2001 Last Revision November 7, 2001 Abstract The natural shrinkage that occurs during the solidification of Ductile Iron can be offset by the expansion caused by the formation of graphite. Though this has been known for some time, thermal analysis has some interesting contributions to understanding exactly what is going on, and offers some opportunities for better control of late graphite expansion in moderate section sizes. Different modes of solidification are examined and measured, and the early and late graphite content are calculated using thermal analysis. Carbon flotation is seen as a fourth form of solidification that is both hypereutectic and hypoeutectic. Introduction to Macro-shrinkage and Expansion Ductile Iron consists of primarily two materials: a steel matrix surrounding graphitic nodules. The steel matrix can be ferritic, pearlitic or martensitic, or a combination of any two. The majority of ductile castings are generally ferritic with less than 10% pearlite. A small amount of retained austenite is generally present and in combination with micro carbides, retains about 20% of the carbon1. This carbon can then be transformed into graphite during heat-treating. The steel matrix will typically shrink 1.2 % when cooling from 2000 degrees to room temperature. Offsetting this is the transformation of dissolved carbon into nodules of graphite, which occupy 12% more volume as graphite than as carbon. One insidious form of shrinkage is a suck-in. It is caused by the same factors as shrinkage, but shows no internal porosity as the volume loss is transferred to the surface of the casting. Suck-ins are caused by the combination of a high shrinkage iron, and a thin or weak casting wall that cannot resist the internal pull. This could be due to a combination of a casting designed hot spot and/or hotter than normal iron. Eutectic and hypereutectic iron is more susceptible to this problem than hypoeutectic iron. Though these castings might not show internal shrinkage, they should be counted as having shrinkage nonetheless. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Two other forms of voids appear in iron: micro-shrinkage, and gas or blows. The micro-shrinkage appears in the grain boundaries as the final solidification takes place, and is caused by micro-segregation where the grain boundaries become enriched in low melting elements and phases 8. Gas is caused by Nitrogen and Hydrogen being present in the iron 9. Figure 1. These are three examples of different levels of macro-shrinkage in thermal analysis cups. Shrinkage occurs at the point of the last metal to solidify, so is located around the thermal couple for easy detection. Some suck-in occurred in samples 4B and 3B. Literature Review file:///c /WEBSHARE/062013/magazine/2001_3/offsetting.htm[6/19/ :21:29 AM]

19 The Ductile Iron News - Offsetting Macro-shrinkage in Ductile Iron Skaland and Grong1 suggest that up to 20% of the carbon in iron does not transform to graphite or pearlite, but is tied up as micro partials of carbides that only convert to graphite on heat treating. They base this on the results of studies of heat-treating, which increases both the total graphite and the nodule count. This suggests that 20% of the carbon present must be discounted, as it will not form graphite during solidification. Heine 3 suggests that higher nodule counts lead to less shrinkage, but that above about 4.70, carbon floatation sets in, and then the nodule counts will vary greatly from the depleted zone to the flotation zone. He also reported two Liquidus arrests in strongly hypereutectic irons 4. Stefanescu et al 5 suggest that shrinkage be broken down into macro-shrinkage caused by feeding problems, micro-shrinkage caused by contraction of the solid metal, and by micro-porosity caused by gas evolution within the iron. In this paper, we will use Stefanescu's definitions of shrinkage and examine what can be done to minimize macro-shrinkage. Komkowski 12 in a Master's thesis found that by deoxidizing iron, he could cause significant undercooling of the austenite arrest. This agrees with the early research by Alagarsamy 13 on the oxygen effect on the Liquidus temperature. This research showed that the presence of oxygen raised the liquidus temperature. While Alagarsamy suggested oxygen raised the liquidus measurement, Komkowski suggests that the oxygen was simply the nucleant that prevented undercooling of the liquidus and that the oxidized state was equivalant to the steady state. In current practice, one manufacturer of thermal analysis cups uses pure tellurium metal in a capsule, one uses an exposed tellurium that will oxidize, one uses tellurium mixed with calcium bearing bentonite, and one uses tellurium mixed with a small amount of iron oxide. The calciumbearing cup has been seen to under cool during the liquidus. This is an important consideration in the current practice of using an inoculant that contains up to 6% Calcium. Since calcium is the strongest deoxidant available for molten iron, it could be expected to suppress the formation of dendrites in the casting, and lead to greater undercooling. Graphite Growth in Solidifying Iron Graphite is a hexagonal-closepack form of carbon that can grow in both the liquid and solid forms of iron. In theory, in irons above the eutectic composition of carbon, the graphite first nucleates in the liquid, and then continues to grow in the solid. In irons below the eutectic composition, the graphite does not start to grow until the iron reaches eutectic temperature. As seen in a micro, the larger nodules are from growth initiated in the liquid, and the smaller nodules are from growth that does not start until solidification temperatures are reached. During heat-treating, the existing nodules increase in size, and very small nodules appear 1. The graphite nodules that form in the liquid in hypereutectic irons continue to grow as the iron cools, so the amount of growth that occurs in the liquid is smaller than what would be assumed by examining the micro. The expansion from the graphite that grows in the liquid, generally pushes liquid back into the riser or down sprue, and does not offset shrinkage. This is because hypereutectic irons do not form thick walls before the eutectic temperature is reached, and of course, there are no dendrites to block this reverse feeding. Late graphite is defined as graphite that grows during or after the eutectic solidification. This late graphite can exert internal pressure to offset the shrinkage we would like to prevent. So in order to minimize shrinkage, it is necessary to maximize the formation of late graphite without having to reduce the actual amount of graphite. Understanding what happens in a non-steady state solidification of Ductile Iron suggests a few ways that this can be done. In a hypoeutectic mode of solidification, austenite forms as a solid with a lower than average carbon content. This increases the carbon content of the remaining liquid until it reaches the eutectic composition. Likewise, in a hypereutectic mode of solidification, graphite nodules form in the liquid, removing carbon from the liquid until it is reduced to the eutectic composition file:///c /WEBSHARE/062013/magazine/2001_3/offsetting.htm[6/19/ :21:29 AM]

20 Figure 2. Phase diagram showing movement of carbon concentration in liquid metal as iron solidifies. It would seem from figure 2 that the maximum amount of carbon that can be formed in late graphite is determined by the eutectic composition, and as long as the iron is at eutectic or above, the amount of late graphite will be the same. But there are some methods that can actually increase the amount of late graphite. The first is to reduce the silicon, the second is to reduce the pearlite, and the third is to run slightly hypereutectic and make use of magnesium's ability to suppress the formation of graphite. The first two methods will also significantly change the properties of the iron, so they may not be possible to implement. The third, which involves running a C.E. from 4.40 to 4.55, opens some possibilities. Thermal Analysis shows how this third method works and how it actually decreases shrinkage. TA also shows the pitfalls of higher C.E.s and where adding more carbon may actually increase shrinkage. Increasing Graphite to Avoid Shrinkage Thermal analysis reveals that under dynamic conditions, the amount of late graphite can be increased considerably by hitting a hypereutectic chemistry between 4.33 and 4.60 that solidifies without a graphitic liquidus. To actually benefit from this window, the C.E. should be slightly hypereutectic (4.4+) and safely away from a higher C.E. that would form a graphitic liquidus. Our research indicates that this point is about 4.6+, though it may change with section size and magnesium level. In qualifying curve types in thermal analysis, there are three basic shapes: One that shows an austenitic liquidus and a eutectic arrest, one that shows a graphitic liquidus and eutectic arrest, and one that only shows a eutectic arrest. Surprisingly, the eutectic only mode is very common in iron used for small and medium size casings. When testing the chemistry for these eutectic only irons, it was found that the carbon equivalent varied from the eutectic composition of 4.33 all the way up to The samples above 4.66 carbon equivalent generally show a graphite liquidus. It is speculated that the magnesium is inhibiting the graphite liquidus up to about a 4.6 carbon equivalent. The level of magnesium in the iron may also have an effect on how much of a carbon equivalent can be suppressed. This means that an iron with a C.E. of 4.55 can behave as a eutectic iron but will add an additional 22 points of carbon to counteract the shrinkage. But an iron with a C.E. of 4.65 will behave not much differently than one of 4.33 C.E. in suppressing shrinkage. C.E. Silicon Carbon Graphite In Liquid Late Graphite Improvement Over Eutectic C.E. Silicon Carbon Graphite In Liquid Late Graphite Improvement Over Eutectic % % % Base Line % % % % %

21 % % % Figure 3. Assumptions: 20% carbon retained in matrix, no graphitic liquidus forms till above 4.60 C.E. Above 4.70 C.E. there is a risk of carbon flotation. This would account for the frequency that eutectic freezing modes are found. The Eutectic is no longer just a point, but a small range from 4.33 to about 4.60 due to the presence of magnesium. This can result in an increase of 13% more carbon forming in the late solidification, or shrinkage being reduced by 1.6% of the total volume of the carbon. This suggests that the amount of shrinkage in castings can vary considerably over a small carbon range. Figure 4. Expanded region of eutectic zone due to magnesium suppression of graphite formation. Once the carbon equivalent becomes higher than the suppressed value, then the effect will be lost, the extra carbon will be removed by graphite formed in the liquid, and macro-shrinkage will increase. This goes against the idea of counteracting shrinkage by simply increasing the carbon content. It suggests that we, instead, should increase the carbon until the iron is slightly hypereutectic, but does not yet exhibit a graphite liquidus. Carbon Flotation in small castings As the carbon content increases into the graphitic liquidus area, a stronger graphitic liquidus occurs that may not simply reduce the carbon content to eutectic, but may actually remove enough carbon to reduce the C.E. level below the eutectic. This results in an unusual thermal analysis curve that has both a graphitic liquidus and an austenite liquidus followed by the eutectic arrest. This then proves even further that increasing the carbon beyond the graphitic liquidus may drastically increase shrinkage. Heine and others have previously documented multiple arrests in their research, but these arrests were not identified as anything other than graphitic arrests4. This is the first time that multiple liquidus arrests have been identified in a single sample. The dynamics of inoculation, magnesium, carbon content, and other alloys make a system that needs to be tightly controlled to supply the necessary amount of carbon and alloys and yet prevent a graphitic liquidus from increasing shrinkage and porosity. Results Samples were taken from many foundries in this research. Two are presented as demonstrating the interrelationships of freezing mode, shrinkage, late graphite and nodule count. The results are from the thermal analysis instrument using the same calibration for both foundries. While the readings are approximant, they are in agreement with the measurements of the foundries, i.e. the 77% nodularity was recorded as an 80%. Table 1 and 2 show typical results from two different foundries having different chemistry aims and inoculation practices. The test data shows considerable interrelationship between shrinkage, and nodule count in the hypoeutectic irons, and in table 1, the shrinkage seems to be related to both nodule count, and the double arrest. The Hypo-hypereutectic arrest in table 1 greatly reduced the available late graphite and increased the shrinkage. The nodule count relates well to the nodularity. This foundry would do well to reduce their carbon slightly and avoid hypereutectic freezing modes. Late graphite control would greatly benefit shrinkage in this foundry. le:///c /WEBSHARE/062013/magazine/2001_3/offsetting.htm[6/19/ :21:29 AM]

22 he Ductile Iron News - Offsetting Macro-shrinkage in Ductile Iron Mode Nodularity Nod Count Late Graphite Shrink Undercooling Eutectic Hypoeutectic Hypo-Hyper Eutectic Hyper Hyper nm 9 Table 1 Generally hypereutectic iron (nm - not measured) In table 2 there is a completely different chemistry practice with a slightly higher inoculation practice. Late graphite comes out during about 93% of the solidification, but it is not enough to offset the lower carbon level and higher inoculation practice. This foundry would do well to decrease their inoculation down to the 300 levels if possible. If chill problems prevent this, then they might consider raising the C.E. to produce eutectic mode solidification. Mode Nodularity Nod Count Late Graphite Shrink Undercooling Hypoeutectic Nm 1 Hypoeutectic Hypoeutectic Hypoeutectic Hypoeutectic Hypoeutectic Hypoeutectic Hypoeutectic Hypoeutectic Table 2 Generally hypoeutectic iron (nm - not measured) Discussion Shrinkage has many causes. The question is: Is shrinkage an intermittent problem or a consistent problem? Consistent problems are problems that require a redesign of the gating and risering system, additions of chills, and even a redesign of the casting or change in the carbon equivalent of the iron. An intermittent problem is generally where the foundry man is at a loss for a solution. While tramp elements that cause significant alloy segregation in the grain boundaries 8 can cause small micro-shrinkage by lowering the grain boundary freezing temperature, this discussion is directed more toward graphite control to offset normal macro-shrinkage. There are four solidification modes that can occur in ductile iron: hypoeutectic, hypereutectic, eutectic, and a combination of hyper-hypoeutectic. These classifications are applied to the shape of the thermal analysis curve, not the chemistry. These curves may differ from what can be expected from chemistry because of the speed of cooling and the suppression of graphite formation due to magnesium. Faster cooling will shift the mode from hypereutectic toward eutectic, and from eutectic toward hypoeutectic. In the hypoeutectic mode there is an austenitic liquidus arrest, followed by a eutectic arrest. In the hypereutectic mode there is a graphitic liquidus arrest followed then by a eutectic arrest. In the eutectic mode there is only a eutectic arrest. In the hyper-hypoeutectic mode there is first a graphitic liquidus arrest followed by an austenitic liquidus arrest, and then finally, the eutectic arrest. Hypereutectic Mode In a hypereutectic mode iron, graphite nodules first form in the liquid. This is a moderately low energy reaction that may go on for some time. The heat generated from the graphite slows the cooling rate, and therefore prolongs the length of the arrest. Since no solid metal is precipitated during this arrest, the walls of the casting are thin to non-existent depending on the temperature gradient. During this cooling time, the expansion due to the graphite may simply push iron back into the riser, or, if it is a riserless casting or the gating is frozen off, will cause some mold wall movement, if the wall is still thin or the liquid is still a large portion of the casting. Since hypereutectic irons will not form thick casting walls le:///c /WEBSHARE/062013/magazine/2001_3/offsetting.htm[6/19/ :21:29 AM]

23 he Ductile Iron News - Offsetting Macro-shrinkage in Ductile Iron before entering the eutectic arrest, they should be risered, or there will be mold wall movement! This goes against conventional thinking, but such previous thinking was probably based on hypereutectic chemistry, and a eutectic freezing mode where no graphite forms in the liquid. The formation of graphite nodules in the liquid reduces the remaining carbon in the iron down to the eutectic level. Assuming a 3.9 carbon and a 2.4 silicon iron (C.E. of 4.7), this will lead to a carbon level remaining in the liquid of 3.53% with the balance of 0.37% going to expansion in the liquid riser or mold wall movement C.E. - (2.4 Si / 3) = 3.53 C Figure 4. Hypereutectic liquid iron is depleted of carbon down to the eutectic point by formation of graphite Once the graphite liquidus is finished, the eutectic forms and the remaining carbon down to the capability of the austenite to hold carbon (2% C.E.) is rejected from the austenite in the form of graphite. Again assuming a 3.9 carbon and a 2.4 silicon iron, this will lead to the formation of about 2.7% graphite in the iron at eutectic. 2.0 C.E. - (2.4 Si / 3) = 1.2 % C in austenite 3.9 C graphite C in austenite = 2.33% graphite formed at eutectic temperature 3.9 C graphite in liquid retained carbon = 2.75 graphite for expansion. Figure 5. Note the large area of the graphitic arrest in the Cooling Rate graphic. This represents a considerable amount of graphite coming out. The energy production of the graphitic liquidus is not as great as an austenite liquidus. This iron would be subject to macro-shrink, but the micro-shrink is ok. The graphite shape is also poor with several clusters of fast growing graphite present. The remainder of the carbon can transform into graphite as the iron cools further. The amount of retained carbon in the unheat-treated room temperature iron is about 20%1 plus whatever carbon is retained in pearlite or carbides. If we assume no pearlite, then the total expansion of the graphite that benefits fighting shrinkage would be 2.75%, and the wasted graphite expansion would be 0.36% or 13% of the total expansion of graphite. Hypoeutectic Mode In a hypoeutectic mode, an austenite liquidus forms, and dendrites grow into the liquid, increasing the carbon content of the remaining liquid. This iron will develop a stronger casting wall to resist mold wall movement, but will have less graphite formed to offset macro-shrinkage. For an iron with 3.4 carbon and 2.1 Silicon (C.E. of 4.1), a little less than 10% of the casting will be solid before the eutectic is reached. 2x + (1-x)* 4.33 = 4.1 C.E. (lever rule)

24 x = 9.87% At the eutectic, the graphite formed would be 2.1% 2.0 C.E. - (2.1 Si / 3) = 1.3 % C in austenite 3.4 C C in austenite = 2.1% graphite formed at eutectic temperature 3.4 C retained carbon = 2.72 graphite for expansion. Applying similar logic to the previous example, we would gain a total of 2.72% graphite to fight expansion. This is not much different than the hypereutectic mode result. Figure 6. Hypoeutectic mode solidification: austenite liquidus and eutectic Eutectic Mode In the eutectic mode, there is no liquidus arrest. Due to the presence of magnesium, a single arrest (eutectic) mode can occur between 4.3 C.E. and as high as a 4.6 C.E. Assuming 2.4 silicon, this iron could contain from a 3.5 to a 3.8 carbon. At the eutectic, this would produce a range from 2.3 to 2.6% graphite: a variation of 13%. 2.0 C.E. - (2.4 Si / 3) = 1.2 % carbon in austenite 3.5 C C in austenite = 2.30% graphite formed at eutectic temperature 3.8 C C in austenite = 2.60% graphite formed at eutectic temperature 3.5 C retained carbon = 2.80% graphite for expansion. 3.8 C retained carbon = 3.04% graphite for expansion. Applying similar logic to the previous examples, we would gain a total of between 2.80% and 3.04% graphite to fight expansion. There is no liquid expansion problem, and the 3.8% carbon example has 13% more beneficial graphite then the slightly higher 3.9% carbon hypereutectic iron. Figure 7. Single arrest eutectic mode solidification Hyper-Hypoeutectic Mode This mode occurs more often than suspected. A large graphitic liquidus starts a reaction that removes so much carbon from the liquid, (possibly through flotation) that the remaining liquid turns hypoeutectic, and an austenite liquidus follows. This material has the worst aspects of a hypereutectic iron (mold wall movement,

25 no appreciable wall thickness, low graphite contribution to fight shrink) and has all the bad aspects of a hypoeutectic iron (even lower graphite contribution to fight shrink). Figure 8. Expanded region of eutectic zone due to magnesium suppression of graphite formation. Assuming a 3.9 carbon and a 2.4 silicon iron (C.E. of 4.7), and that the iron falls to a 4.25 C.E. this will lead to a carbon level remaining in the liquid of 3.45% with the balance of 0.45% going to expansion in the liquid riser or mold wall movement C.E. - (2.4 Si / 3) = 3.45 C The eutectic forms, and the remaining carbon down to the capability of the austenite to hold carbon (2% C.E.) is rejected from the austenite in the form of graphite. Again assuming a 3.9 carbon and a 2.4 silicon iron, this will lead to the formation of about 2.6% graphite in the iron at eutectic. 2.0 C.E. - (2.4 Si / 3) = 1.2 % carbon in austenite 3.9 C graphite in liquid C in austenite = 2.25% graphite formed at eutectic temperature 3.9 C graphite in liquid retained carbon = 2.67 graphite for expansion. The remainder of the carbon can transform into graphite as the iron cools further. The amount of retained carbon in the unheat-treated room temperature iron is about 20%1 plus whatever carbon is retained in pearlite or carbides. If we assume no pearlite, then the total expansion of the graphite that benefits fighting shrinkage will be 2.67%, and the wasted graphite expansion will be 0.45% or 17% of the total expansion of graphite. Figure 9. The two liquidus arrests are followed by the eutectic arrest. The first liquidus arrest is large but not energetic (graphitic). The second liquidus arrest is small but very energetic (austenite). Conclusion Macro-shrinkage is the result of the interaction of several complex influences in the iron. If the shrinkage is constantly present from day to day, then the gating and risering vs. the iron chemistry needs to be revised. But if the problem comes and goes, and the chemistry seems to be consistent during these episodes of shrinkage, then the problem is most likely in the control and timing of the graphitizing process. Magnesium opens up the C.E. range of a eutectic iron by inhibiting the formation of a graphite liquidus. This opens up the possibility to have more carbon in the iron to offset shrinkage so long as no graphitic liquidus occurs. This phenomena needs to be studied more in terms of effective magnesium vs. carbon level vs. inoculation. Calcium further changes the nucleation of the iron by inhibiting the formation of austenite dendrites and promoting a single heavily under cooled eutectic arrest. le:///c /WEBSHARE/062013/magazine/2001_3/offsetting.htm[6/19/ :21:29 AM]

26 1. T. Skaland and O. Grong: "Nodule Distribution in Ductile Cast Iron," AFS Transactions 91-56, p (1991). 2. Torbjorn Skaland: A Model for the Graphite Formation in Ductile Cast Iron, University of Thronheim, Norway. (1992) 3. R.W. Heine: "Nodule Count: The Benchmark of Ductile Iron Solidification," AFS Transactions 93-84, p 879 (1993) 4. R.W. Heine: "Carbon, Silicon, Carbon Equivalent, Solidification, and Thermal Analysis Relationships in Gray and Ductile Cast Irons," AFS Transactions 72-82, p 462 (1972) 5. D.M Stefanescu, H.Q. Qiu and C.H. Chen: "Effects of selected metal and mold variables on the dispersed shrinkage in spheroidal graphitic cast iron," AFS Transactions , p 189 (1995) 6. T.N. Blackman: "Graphite Flotation in Ductile Iron Castings," AFS Special Report (1988) 7. A.G. Fuller, T.N. Blackman: "Effects of Composition and Foundry Process Variables on Graphite Flotation in Hypereutectic Ductile Irons," AFS Special Report (1988) 8. R. Boeri, F. Weinberg: "Microsegregation in Ductile Iron," AFS Transactions , p 179 (1989) 9. Richard Fruehan: "Gases in Metals," ASM Handbook volume 15 Castings, p 82 (1992) 10. D.A. Sparkman, C.A. Bhaskaran: "Chill Measurement by Thermal Analysis," AFS Transactions , p 969 (1996) 11. David Sparkman: "Using Thermal Analysis Practically in Iron Casting," Modern Castings November 1992, p Carsten Komkowski: unpublished Masters thesis work on deoxidation of Iron, Kiel, Germany. 13. A.Alagarsamy, F.Jacobs, G.Strong, R.Heine: "Carbon Equivalent vs. Austenite Liquidus: What is the he Ductile Iron News - Offsetting Macro-shrinkage in Ductile Iron Small-localized carbon flotation may be far more common than previously thought, and can result in slow cooling sections anytime that the graphitic liquidus occurs in that section size. This can account for 15 to 20% less graphite being available to counteract the macro-shrinkage. This can also occur in iron when the carbon equivalent is on the high side of safe, and the effective magnesium is on the low side of the normal operating range. Inoculation may also influence the appearance of the graphitic liquidus. The eutectic mode of freezing with irons that are above the eutectic in chemistry will give the most "late graphite" to counteract macro-shrinkage. There is as much as a 13% gain in late graphite possible with this mode of solidification. Likewise, irons of the same C.E. level that are lower in silicon will have more graphite to counteract shrinkage. Thermal analysis provides a unique picture of how all these factors combine together to produce different modes of freezing. It can identify irons susceptible to carbon flotation, as well as when the iron will have a graphitic liquidus. References Before and after in-stream inoculation

27 correct Relationship for Cast Irons" AFS Transactions 84-31, p 871 (1984) View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org le:///c /WEBSHARE/062013/magazine/2001_3/offsetting.htm[6/19/ :21:29 AM]

28 he Ductile Iron News - Near Net Shape DI Components To Promote the production and application of ductile iron castings Issue 3, 2001 Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming by: P.H. Mani Introduction: Nearly all metals and alloys of commercial importance solidify dendritically, either with a columnar or with an equiaxed dendritic structure. When an alloy that normally solidifies dendritically is vigorously stirred during solidification, the dendritic structure can be broken up and replaced by the more or less spherical structure. The resulting semi-solid structure deforms homogeneously and can be formed into shapes by several methods. Semi-solid forming is the generic term applied to a process in which a mixture of solid and liquid phase metal is introduced into a mold or a die for net shape forming. One might think of the process as a hybrid between casting and forging and because the equipment used more closely resembles the die casting process. Semi-solid manufacturing seems to have fallen into the domain of metal casters. Semi-solid processing of non-ferrous alloys, especially Aluminum alloys are in production phase for many critical automotive components. They have taken a bite on the traditional market share of ferrous components, especially ductile iron. However, the possibility of near net shaping of high melting point alloys in the semi-solid state has already been demonstrated. This paper presents the results of the possibilities of making semi-solid processed ductile iron components and the potential applications for such components. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Semi-solid processing of 'as cast' ductile iron slugs: It was decided to manufacture a series of ductile iron gears (cog wheels) using the semi-solid forming technique. Fig 1 shows the drawing of the proposed gear. Figure 1. Gear (cog wheel) Material: Ferritic Ductile Iron

29 The chemistry of the slugs is as follows: Element % Element % Carbon 3.65 Silicon 2.63 Manganese 0.29 Chromium 0.03 Aluminum 0.01 Sulfur Phos Copper Nickel 0.02 Magnesium Moly less than 0.01 Tin less than 0.01 Titanium less than 0.01 The slugs were machined to a dimension of 58mm diameter by 80mm height. A graphite die was machined to the shape of the gear. A D2 Steel die or any other metallic die would be used in production. The machined slugs were placed inside the induction coil with the thermocouple inserted in position. See Figs 2,3,4 for the set up. Figure 2. Experimental arrangement for heating trials of ductile iron slug.

30 Figure 3 Figure 4. Hot slug traveling towards die cavity

31 Nitrogen was used as an inert gas to provide the inert atmosphere inside the coil. By having the slugs in the center of the induction coil and having the top and bottom of the slugs insulated with insulating pads after the 'soaking' period the radial temperature difference was around o F (approximately 5 o C) and the axial temperature difference was around o F (12-15 o C). This temperature difference appears to be sufficient to allow semi-solid forming of the ductile iron slugs within the processing window. The as-cast slug was first heated to a temperature of 2120 o F (1160 o C) for about 170 seconds and then further heated to a temperature of 2138 o F(1170 o C) and held at this temperature for another 90 seconds. The dwell time when the forging load was applied was set to 30 seconds. The slug was injected into the die in this condition to produce the gears. Fig 5&6 shows the gears made by this process. Figures 5 and 6. S.S.M. (Thixoformed) ductile iron cog wheels (gears) The presence of carbides in the microstructure due to rapid cooling of the liquid fraction of the slug during the semi solid forming is eliminated by 'synchronized' annealing above the critical temperature. le:///c /WEBSHARE/062013/magazine/2001_3/nearnet.htm[6/19/ :21:27 AM]

32 he Ductile Iron News - Near Net Shape DI Components Semi solid formed components can be austempered in 'tandem' with this process to obtain high strength, high toughness properties. In addition to ductile iron, compacted graphite iron can be semi-solid formed to near net shapes. View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

33 he Ductile Iron News - Shrinkage in Nodular Iron To Promote the production and application of ductile iron castings Issue 3, 2001 Shrinkage in Nodular Iron Eli David Senior Manager Technical Services, Globe Metallurgical With increasing complexity in casting geometry and continued stringent requirements for completely sound castings, understanding and predicting the shrinkage behavior of ductile cast iron parts is all the more crucial for successful foundry operations. Four distinct regions can be isolated when observing ductile iron solidify. A. Liquid contraction from the superheat temperature to the liquidus. This contraction is very predictable since it is dependent on the coefficient of expansion of the alloy (generally around 1.5% by volume per 100 o C). B. Liquid shrinkage through the liquidus temperature. A phase change takes place at this juncture. A portion of the liquid iron transforms to solid austenite. Occasionally for highly hypereutectic irons graphite precipitates at the liquidus instead of austenite, resulting in expansion rather than contraction. C. Eutectic expansion follows the liquidus. The remaining liquid transforms into austenite and graphite. Expansion always occurs during the eutectic transformation and it is very significant. This is because all of the carbon in the liquid iron minus the carbon dissolved in the austenite precipitates as graphite during the eutectic. The volume fraction of graphite (in the eutectic) that precipitates can be calculated using the lever rule. For an iron with a typical 3.65% carbon (Co =3.65%) the fraction percent of graphite in the eutectic is as follows: G/G+g = Co-Cg/CG-Cg = ( )/( ) = 1.78% The eutectic consists of 98.22% austenite and 1.78% graphite by weight. The amount of carbon dissolved in the austenite is roughly 1.90%. Therefore of the 3.65% compositional carbon, 1.87% is dissolved in the austenite and 1.78% precipitates, hopefully, as graphite. Graphite has a much higher specific volume compared to iron causing the expansion that is observed. The density of graphite is 2.2 g/cc compared to 7 g/cc for that of iron. D. Solid contraction is also dependent on the expansion coefficient. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, These changes are depicted schematically in Fig.1 for three different irons. The following should be noted: a. All three irons undergo a net expansion during solidification. The volume of the solidified iron at the end of solidification (before solid contraction) is greater than the volume of the liquid poured into the mold!

34 b. Hypereutectic ductile irons have been measured to exhibit volumetric expansion as high as 4%. c. For the same carbon equivalent ductile will expand more than gray. d. Feed metal must be supplied by risers and/or the gating system for all cast irons in zone A. Additional feed metal must be provided in zone B for hypoeutectic irons. e. The reason eutectic expansion cannot be effectively utilized to compensate for earlier contraction and shrinkage is that green sand mold walls dilate (move outward) when subject to the enormous expansion forces. Note (in Fig. 2) that at the end of solidification when the metal contracts the mold wall stays at its maximum dilated position. Solidification Mechanisms: Cast iron solidification is very different from that of a pure metal. Pure metals solidify with a solidification front that is very well defined and a clearly delineated solid liquid interface. Ductile cast iron solidification, on the other hand, is characterized by a very thin solidified skin and if conditions are not optimal a large mushy zone. The outer skin formed during gray cast iron solidification is much heavier than that of ductile. Flake graphite is a better conductor of heat compared to nodular. The heavier skin prevents the transmission of the eutectic expansion forces to the mold walls. This is the reason why gray irons need less risering than ductile even though ductile iron solidification results in a larger net expansion. The width of the mushy zone and the aspect ratio of the austenite dendrites have been linked to the feeding capability of the riser. Generally short stubby dendrites in a narrower mushy zone will produce better feeding characteristics. Narrower mushy zones are obtained when nodular iron solidifies as a eutectic with very little separation between the liquidus and eutectic temperatures. Austenite that precipitates during the liquidus tends to grow much larger in size. Finer eutectic austenite is also believed to improve feeding capability and to be associated with higher nodule counts. Most foundry engineers have to rely on experience or guess at how far a particular riser will feed. Even though research has produced test patterns that can evaluate feeding distances, very few foundries take the time to evaluate this key variable. The problem is compounded particularly since the mushy zone changes from tap to tap depending on the metallurgy and quality of the iron. Therefore the feeding distance itself is a function of the metallurgical integrity of the iron. Comparative Solidification Schematic - Fig. 3

35 For the purposes of this paper shrinkage will be divided into four categories: 1. Pull downs or suckins. 2. Macro shrink larger than 5 mm 3. Micro shrink or shrinkage porosity less than 3 mm 4. Microscopic grain boundary shrinkage. Generally only visible under a microscope at a magnification greater than 100X. Fig. 4 The current paper will focus on the first three types only. These defects occur at very different and distinct times during solidification as depicted in Fig.5. le:///c /WEBSHARE/062013/magazine/2001_3/elidavid.htm[6/19/ :21:24 AM]

36 he Ductile Iron News - Shrinkage in Nodular Iron Thermal analysis is probably the strongest tool available in the foundry man's arsenal to understand and combat shrinkage defects. For example a high value for the area S1 is associated with a lot of primary austenite and a large mushy zone and therefore with an iron that is more likely to produce pull down and macro shrinkage upon solidification. In fact large variations in S1 have been observed from treatment batch to batch (before post inoculation) in the same foundry on the very same day. Base iron holding time appears to be the single most dominant variable contributing to this deviation. Strong post inoculation appears to mitigate the variance in S1. Pull downs or suckins are produced very early in solidification. The skin formed at the top cope surface is extremely thin. If feed metal is not provided then contraction will cause a negative pressure just below the skin. The atmospheric pressure then pushes the wall inward producing the "pull down" or "outer sunk" defect Macro shrink generally appears a little later. The skin formed is thick enough and will not cave in. The negative pressure consequently produces rather large shrink holes. If this defect appears at the riser contact or inside the casting cavity relatively close to the riser (as it generally does) proper risering technique can and should be utilized to solve the problem. The first observation when trouble-shooting macro shrink should be "Did the riser pipe?" The remedies applied are very different depending on whether the riser piped or not. If the riser piped properly then possible solutions are: 1. Increase riser size 2. Check carbon equivalent. It may be too low 3. Lower pouring temperature However, if the riser did not pipe then the analysis is not as straight forward and the following are recommended: 1. Reduce riser contact modulus. The contact modulus may be too large keeping the contact open during the casting eutectic expansion leading to back feeding. 2. Reduce the modulus of the ingate feeding the riser. If the ingate stays open too long initial feed metal will be delivered to the casting cavity from the gating system rather than the riser. The top of the riser will then freeze off le:///c /WEBSHARE/062013/magazine/2001_3/elidavid.htm[6/19/ :21:24 AM]

37 he Ductile Iron News - Shrinkage in Nodular Iron preventing proper piping. Conical risers are particularly vulnerable to this phenomenon. 3. Check carbon equivalent. It may be too high 4. There may be too many risers present 5. Pouring temperature may be too cold If macro shrink appears infrequently and intermittently (comes and goes) and still within the known limit of the risers feeding capability, then variations in metallurgical integrity (larger mushy zone and S1 inhibiting feeding) or poor sand compaction with soft molds are more than likely the culprits particularly if the chemistry checks out OK. From a chemistry point of view, hypoeutectic irons (both gray and ductile) are far more susceptible to macro shrink and outer sunks. A large separation between liquidus and eutectic (as would be expected with hypoeutectic irons) produces a lot more primary austenite thereby reducing the riser's ability to feed. In ductile irons, which tend to be hypereutectic except when pouring very heavy sections, it is desirable for the casting to freeze as a eutectic alloy i.e. with the liquidus arrest as close as possible to the eutectic. Generally when the liquidus appears at a much higher temperature from that of the eutectic, primary austenite is precipitating from the melt even though the chemical composition is hypereutectic. In ductile irons this happens because of the strong undercooling effects of elements such as magnesium and rare earths. Furthermore, highly oxidizing conditions in the melt coupled with high melting temperatures and long holding times reduce the carbon activity causing a chemically hypereutectic iron to solidify as if it were hypoeutectic. Micro shrinkage porosity appears very late in solidification. At this stage feed paths are well closed. This type of shrink commonly appears on isolated bosses or outside the riser's ability to feed. The only possibility to obtain sound castings is to rely on late eutectic graphite precipitation, with its inherent expansion, to "fill in" the shrinkage voids. Eutectic solidification patterns where most of the graphite comes out early are undesirable. A uniform precipitation pattern is preferred. A good thermal analysis program can help measure such variables. Since it is helpful to have graphite come out late then, by definition, a microstructure with varying nodule sizes (nodule bifurcation) or a bi- modal nodule size distribution will be less likely to produce micro shrink. Graphite that comes out early in the eutectic will grow to a larger size when compared to that of graphite that precipitates toward the end of the eutectic, since the late graphite will not have sufficient time for growth. Care must be taken when evaluating structures since one is viewing a threedimension picture in 2D. The size of any given nodule will not only depend on the nodule size but also where the nodule happened to be sectioned. Furthermore, great care should be taken, when making such analysis, that the bimodal distribution is not due to pre-eutectic graphite precipitation. Pre-eutectic arrests associated with exceedingly hypereutectic irons can also exhibit a bi-modal distribution. Graphite that precipitates during the liquidus generally ends up much larger in size than the eutectic graphite. This is generally an undesirable outcome. Therefore thermal analysis curves should be viewed concurrently with the microstructure. Furthermore, several late solidification phenomena can also be evaluated from the cooling curves. These will not be discussed in this paper other than to add that they are invaluable in determining the amount of graphite that precipitates late in the eutectic and therefore the susceptibility of the iron to micro shrinkage defects. General Foundry Practice: There can be no substitute for good common sense foundry practice. Avoid super heating, long holding times, oxidized charge materials and poorly compacted soft molds. Keep carbon as high as possible, silicon maintained at the lower end of normal operational ranges, appears to reduce shrink defects. Residual magnesium should be maintained at levels to ensure proper nodularity and no higher. Rare Earth elements should be optimized depending on the level of tramp elements such as sulfur, oxygen and bismuth (if added). Inoculant addition should be precisely controlled and the type and quantity should be optimized. Clamping cope and drag molds will help reduce shrink defects. For flask less molding ensure that mold weighting is sufficient.

38 The Ductile Iron News - Solving Casting Problems with New Sleeve Technology To Promote the production and application of ductile iron castings Issue 3, 2001 Solving Casting Problems with New Sleeve Technology Ronald C. Aufderheide Ralph E. Showman Foundry Products Division Ashland Specialty Chemical Company Division of Ashland Inc. Abstract Foundrymen are constantly being confronted with challenges to improve their operations and lower costs while at the same time producing higher quality castings. One of the ways to achieve lower costs and improve the soundness of a casting is to incorporate the use of exothermic riser sleeves. This can lead to improved yield while solving shrinkage problems. However, at the same time, the use of exothermic riser sleeves can create other problems. This paper will discuss two defects that, under certain conditions, can be created by the use of exothermic riser sleeves in ductile iron. The first defect is a surface "fish-eye" defect that is caused by the buildup of exothermic sleeve material in the molding sand. This defect doesn't occur on a casting just because it is made using exothermic sleeves; rather, it occurs on the ductile iron castings that are made with sand that has been contaminated with exothermic sleeve materials. Tests showed that the presence of fluorine in the exothermic sleeve formulations contributed to the formation of fish-eye defects. A new exothermic sleeve was developed that did not contain fluorine and that eliminated the fish-eye defect. The second defect is a degradation of the graphite nodules in ductile iron castings. Testing showed that the amount of flake graphite is related to the type and composition of the exothermic sleeve. The degradation was highest when sandbased exothermic sleeves were used. Fiber-based exothermic sleeves produced slightly less degradation, and the new-technology cold box-based fiber-free and fluorine-free exothermic sleeves produced the least amount of degradation when exothermic sleeves were used. Insulating riser sleeves did not show any degradation tendencies. Depending upon the type of exothermic sleeves used, special considerations need to be made with respect to the placement, size, and quantity of sleeves used so that no contaminated metal gets into the casting itself. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Introduction Ductile iron castings have unique riser requirements compared to the feeding of other metals. The volume changes in the casting are not a simple contraction as the metal cools. For example, when the graphite nodules are formed, the metal actually expands, which can push metal back into the riser and gating system if these are not properly designed. This, along with the subsequent contraction of the metal as it cools, creates a strong demand on the feeding capabilities of the riser. Now, more than ever, foundries are trying to find ways to reduce their overall cost to produce a casting. One way to reduce costs is to incorporate the use of exothermic sleeves around the risers. This allows the use of smaller risers that improve yield and reduce the contact surface area of the riser to the casting, which costs money to grind off. There are a variety of sizes, shapes, and formulations available in the exothermic category of riser sleeves. Traditionally the sleeves were made of fibrous refractory combined with a blend of materials that produce an exothermic reaction more commonly known as a thermite reaction. The most common fuel material is aluminum. When mixed with an oxidizer and an initiator/fluxing material and exposed to extreme heat, the aluminum is oxidized, giving off heat as the reaction proceeds. file:///c /WEBSHARE/062013/magazine/2001_3/solving.htm[6/19/ :21:32 AM]

39 The Fish-eye Defect The Ductile Iron News - Solving Casting Problems with New Sleeve Technology 2Al + Fe > Al Fe + Heat (Fluoride initiator / Flux + Heat) In addition to fiber-based exothermic sleeves, sand-based exothermic sleeves had been gaining favor with many ductile iron foundries. Sand-based, high-density sleeves are formulated to contain more aluminum fuel and to generate a greater amount of heat. This heat is first required to raise the temperature of the sandbased sleeve, before favorably influencing the temperature of the metal in the riser. Finally, in 1997 Fiber-free New Technology Sleeves were introduced, providing another exothermic sleeve alternative. The refractory material is a round alumina silicate material bonded by cold box resin technology. During the development of this technology, it became apparent that the requirements for an exothermic sleeve for ductile iron applications are different from those for an exothermic sleeve used to make steel castings. This is especially true for cold risers in ductile iron. Cold risers are those risers that are filled with metal after the metal has moved through the casting, as opposed to hot risers that are filled by the gating system before the metal goes into the casting. This makes the metal in the cold riser colder and closer to solidifying. In order to get an exothermic reaction to start, the metal needs to give up some of its energy to the riser sleeve. However, if too much energy is given up, the surface of the riser begins to skin. Once the skin has formed, the exothermic reaction of the riser sleeve is not enough to remelt it, and the riser becomes less efficient in its feeding capabilities. To solve this, a special, fast-igniting exothermic sleeve is needed so that the energy taken out of the metal in the cold riser is minimized. It has been found that cold ductile iron risers exhibit improved performance when their formulation has been optimized so that they ignite at lower temperature and energy levels, have a faster ignition time, and burn at higher temperatures with more energy. The result is a flatter feed pattern in the riser, as shown in Figure #1. Figure #1: Piping of standard exothermic-sleeved riser (Left) versus the flatter feed of a New Technology fast-igniting exothermic sleeve (Right). Increasing the amount of aluminum can increase the heat generated by the riser, but there are some limitations. First of all, after the exothermic reaction is completed, the riser must then rely on its insulating properties to keep the metal in the riser hot. Unfortunately, as more exothermic material is added to the riser formulation, the amount of insulating material is reduced, thereby also reducing the insulating properties after the exothermic reaction is completed. The key is to balance the amount of each to produce the optimum sleeve performance. Sandbased exothermic sleeves are not good insulators. The sand has the same thermal characteristics as the sand mold, so the sandbased exothermic sleeve must rely on the heat of its exotherm. However, the increased use of exothermic sleeves has brought with it a unique set of problems, which is the subject of this article. We will be covering two different defects, both of which are directly affected by the use of exothermic riser sleeves. The fish-eye defect appears on the surface of the casting as a round depression with a raised center, as shown in Figure #2. The second defect that will be discussed is a degradation of the graphite nodule from spherical to flake form. This flake structure can potentially extend into the casting, resulting in severe reductions in the physical properties of the casting and its subsequent performance. This effect was first noted during the microstructure analysis of the fish-eye defect and the further development work on new exothermic sleeve formulations and their effect on ductile iron.

40 Fish-eye defects are unique to ductile iron foundries. Very little is understood about their cause, and even less has been written about them. Before the wide use of exothermic sleeves, fish-eye defects were only seen occasionally in green-sand foundries when an excessive amount of clay balls was present in the Figure #2: Fish-eye Defect sand. With the growing use of exothermic riser sleeves, there has been an increase in the presence of fish-eye defects. It has been found that these defects are linked directly to the use of exothermic riser sleeves. Initially, it was theorized that the fish-eyes were caused by high levels of fluorine in the molding sand, residual unburnt pieces of sleeves in the molding sand, gas reactions from the sleeve materials, and/or sleeve materials coming in contact with the casting surface. In order to determine the cause, tests were run using five different contamination materials: cryolite, crushed unburnt exothermic riser sleeves, crushed burnt exothermic riser sleeves, crushed 0-Fluorine exothermic sleeves, and crushed insulating sleeves. These contaminants were placed on the pattern surface for one set of tests. For the second set of tests, they were mixed in with green sand and used as facing sand for the test castings. In order to determine the amount of sleeve materials needed to produce a fisheye defect, tests were run on a foundry's sand that actually did produce the defect. With this information, the amount of contamination used in the testing was deliberately set at twice the calculated amount. The first set of tests, where the contamination materials were placed directly on the casting surface, did not create any defects. This was extremely interesting in light of the initial theories of high fluorine levels (from the cryolite initiator material in exothermic sleeves), gas from the sleeve, and/or contact with sleeve material causing the defect. The second set of tests, where the contaminants were mixed in with green sand and used as facing sand to make the casting, were much more informative. Figure #3 shows the contaminated facing sand on the pattern. Table 1 lists the results of these tests. Although fluorine initially was thought to be a major contributor to producing fish-eye defects, in both cases cryolite contamination did not produce a defect. The only time that a defect occurred was when material from a traditional exothermic sleeve was mixed in with the facing sand. However, when the fluorine initiator in the exothermic sleeve was replaced with a nonfluorine-containing initiator, no defects were produced. The defect was also produced regardless of whether the exothermic sleeve was new (as would be the case if a mold wasn't poured and the sleeve was shaken out with the mold in a closed system) or if it was burnt. Figure # 3: Contaminated Facing Sand Table 1: Results of Contamination Study Contaminant Contaminant of Pattern Contaminant in Facing Sand Cryolite No defects No defects Crushed Un-Burnt EX Sleeves No defects Fish-eye Defects Crushed Burnt EX Sleeves No defects Fish-eye Defects Crushed 0-Fluorine EX Sleeves No defects No defects Crushed Insulating Sleeves No defects No defects The results of these tests showed that in order to avoid the formation of fish-eye defects, several things could be done: file:///c /WEBSHARE/062013/magazine/2001_3/solving.htm[6/19/ :21:32 AM]

41 The Ductile Iron News - Solving Casting Problems with New Sleeve Technology Don't pour ductile iron when the sand is contaminated with fluorine containing exothermic sleeves. Dilute contaminated sand before using it to pour ductile iron castings. Avoid using large quantities of fluorine-containing exothermic sleeves. Use insulating sleeves. Use 0-Fluorine exothermic sleeves. Microstructure Degradation During the initial investigation into what caused fish-eye defects, the microstructure of the metal was examined in the areas adjacent to the defect and areas in contact with the exothermic sleeve in the riser. These examinations revealed another problem that wasn't expected. A large percentage of the graphite nodules had degraded into flake graphite. Closer examination showed that the degradation was not limited just to the surface of the metal but extended all the way across the upper portion of the riser itself, as can be seen in Figure #4. An analysis of the metal at the top, center, and base of the riser revealed varying levels of aluminum. Table #2 below lists the carbon, silicon, magnesium, and aluminum levels at three locations within the riser. The aluminum level is extremely high in the top portion of the riser. Typically aluminum levels in excess of about 0.10% will create flake graphite in ductile iron. As the aluminum level goes down, the graphite degradation is reduced. The concern is how much aluminum will the riser pick up and how far down will the graphite degradation extend. In one case, 33% of the riser contained flake graphite. The total amount of aluminum in the metal could continue to build up if not monitored and controlled. High aluminum levels in the metal will not only prevent the formation of graphite nodules, but also can cause pinhole defects in green-sand molding. Figure # 4: Ductile Iron Riser Cross-Sectioned C Si Mg Al Top Center Base <0.01 Table # 2: Analysis of Riser There is good reason for concern since the risers on ductile iron castings represent a high percentage of the base charge for the next metal melted. In addition to the aluminum pickup from exothermic riser sleeves, aluminum also can come from other sources such as inoculants and alloys, as well as from other charge materials. With this in mind, it was decided to investigate the different types of sleeves on the market to see how they compared in terms of aluminum pickup. Table #3 lists the results of how the different types of sleeves affect the amount of flake graphite that is formed in the riser. Sleeve Type % AL at Top % AL at Center % Flake Graphite EX Sand 0.30% 0.047% 33% EX Fiber 0.23% 0.020% 30% Hi-EX New Tech. 0.28% 0.020% 15% Lo-EX New Tech % 0.010% <2% Insulating <0.01% <0.01% None Table #3: Comparison of Aluminum and Flake Graphite with Different Sleeves file:///c /WEBSHARE/062013/magazine/2001_3/solving.htm[6/19/ :21:32 AM]

42 The Ductile Iron News - Solving Casting Problems with New Sleeve Technology Exothermic sand risers showed the highest amount of flake graphite formation, followed by the traditional fiber-based exothermic riser sleeve. Two different fiberfree New Technology exothermic riser sleeves were also run. The "Hi-EX" New Technology sleeve contained a slightly higher level of aluminum than the current production grade that is being sold in the market to try to match the amount of aluminum contamination caused by the exothermic fiber-based riser. Although the amount of aluminum contamination was similar, the graphite degradation was only 15%. A second "Lo-EX" New Technology sleeve, which contained about half the amount of aluminum fuel, was tested, as well as an insulating sleeve which does not contain any aluminum fuel. These showed less than 2% and no flake graphite respectively. There are several ramifications if the flake graphite contamination extends into the ductile iron casting itself. For example, the mechanical properties of the casting, such as tensile strength and ductility, will be reduced, which can cause the part to fail in service. Unfortunately, these problems are not always detected by normal testing. Many ductile iron foundries check the aluminum level in their metal on a regular basis, which is a practice that all foundries should implement. Figure #5 shows a ductile iron yoke production casting that had a dark area on the machined surface on the cope side of the casting. The location was just below an exothermic riser. The initial thoughts were that the casting had not "cleaned-up" and some of the oxidized "as-cast" surface remained. However, further examination of the microstructure below the defect revealed flake and vermicular graphite in the dark areas rather than nodules. Contaminated metal from the riser had apparently fed into the casting, causing the degraded microstructure. Changing the location of the risers solved the problem. Rather than placing an individual riser on top of each casting, a single riser was placed in the runner system between the ingates of two separate castings. This changed the feeding pattern so that no contaminated metal entered into the casting. It also improved the casting yield. Unmachined and machined castings Dark area on machined surface Microstructure in dark area, 100x Microstructure in adjacent area, 100x Figure #5: Production casting showing graphite degradation that extended into the casting Identifying the Causes It has been shown that exothermic sleeves can cause flake graphite within ductile iron risers and that this flake structure can potentially extend into the casting. The next question is how do the different materials in an exothermic sleeve formulation contribute towards the graphite degradation. To answer this question, a design of experiment was performed looking at the percent of total aluminum, type of aluminum, percent of iron oxide, percent of fluorine-containing compounds and the percent of other types of initiators. file:///c /WEBSHARE/062013/magazine/2001_3/solving.htm[6/19/ :21:32 AM]

43 The Ductile Iron News - Solving Casting Problems with New Sleeve Technology The results of the design of experiment showed that the amount of flake graphite was affected by the percent of total aluminum and any other ingredient that either reduced the ignition temperature of the exothermic reaction or increased its burn temperature. As the percent of total aluminum increased, the percentage of flake graphite also increased. In addition, when the ignition temperature decreased or the burn temperature increased, the amount of flake graphite increased. However, it was discovered that when fluorine is taken out of the exothermic sleeve formulation, no flake graphite was formed, even when the ignition temperature of the sleeve was decreased and the burn temperature was increased. Discussion Feeding ductile iron castings requires a higher-performance exothermic riser sleeve than has traditionally been used for steel applications. This is especially true in cold-riser applications where the metal has a chance to cool before it goes into the riser. In coldriser applications, exothermic sleeves that have a lower ignition temperature and burn hotter perform better. This is because of the lower temperature of the metal in the riser and the lower amount of superheat of the metal. This need for faster ignition and hotter-burning exothermic riser sleeves also increased the degradation of the graphite nodules into flake graphite. However, with the development of the 0-Fluorine New Technology riser sleeve, this problem has been solved. In addition, the 0-Fluorine New Technology sleeve solves fish-eye defects created by the contamination of the molding sand with traditional exothermic riser sleeves. The high-performance, 0-Fluorine, New Technology exothermic riser sleeves also provide extremely efficient feeding for ductile iron cold-riser applications. Conclusions Although different in their appearance and formation, Fish-eye defects and ductile iron graphite degradation have one thing in common: they are both influenced by the use of exothermic riser sleeves. Ductile iron graphite degradation is caused by the use of exothermic riser sleeves, and Fish-eye defects are caused by the contamination of the molding sand from the same exothermic riser sleeves. Using 0-fluorine New Technology riser sleeves can prevent both of these defects. Good foundry practices should also be used to choose the best riser location to be able to feed the casting with the smallest riser possible. This will improve the foundry's casting yield and lower its overall cost to produce castings. Acknowledgements Thanks to Ben Carr and Mark Hysell in Ashland's Metals Application Laboratory for their assistance on this project. References "New Developments in Riser Sleeve Technology", R. Aufderheide, R. Showman, H. Twardowska, AFS Transactions, 1998, pp "Graphitization of Pure Fe-C alloy During Annealing", D.N. Khudokormov, V.M. Kordev, Russian Casting Production, Dec. 1967, pp "Observation of Reactions During the Combustion of Exothermic Materials by Differential Thermal Analysis", C. Pelhan, N. Majcen, paper to 1970 International Foundry Congress. "Exothermic Riser Sleeves Can Cause Flake Graphite in Ductile Iron", R. Showman, R. Aufderheide, C. Lute, paper , AFS Casting Congress, Dallas, Foundrymen's Guide to Ductile Iron Microstructures, AFS, Des Plaines, Ill., Metals Handbook Ninth Edition, Volume 15, Casting, ASM International, file:///c /WEBSHARE/062013/magazine/2001_3/solving.htm[6/19/ :21:32 AM]

44 The Ductile Iron News - Basic Metallurgy To Promote the production and application of ductile iron castings Issue 3, 2001 By: Arthur A. Avedisian, P.E. Editor's note Basic Metallurgy The following article was written by a long time friend of the Ductile Iron Society. I am sure that Art Avedisian is remembered by many of the present members. He began his association with the DIS back in the 1960's and has continued to the present time. He has served the Society on the Research Committee, as technical chairman at our T&O meetings and received the DIS Annual Award in His most important contribution to the Society my be the initiation of our present "Ductile Iron News." Art can truly be referred to as the "father" of the present magazine. Art is doing well in his retirement and continues to be active in teaching metallurgy. The following is the chapter on ductile iron that will be included in the book he is writing. He stresses the point that this is for the "metallurgically uneducated" and should be taken as such. For those of you who would ask, "How old is Art now?", I recommend that you give him a call. I will only tell you that he qualifies as the oldest DIS alumni member. Art can be contacted at home. His address is 810 Bookbinder, Windsor, CT The production of ductile irons A few years ago, in my lifetime, ductile iron (nodular iron) was discovered by a wonderful friend named Keith Millis, (now deceased) of the International Nickel Company. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, To set the stage of our story, we know that gray cast iron with its flake graphite exhibits no useful yield in tension, or elongation, and is considered a brittle material. (That is if the student has learned his lessons). Ductile iron, even with its high graphite content, combines the useful properties of gray irons, among them, casting ability, with the high strengths of steels. A new industry was born that has grown to tremendous proportions all over the world! Actually Keith was looking for way to reduce the sulfur in cast irons by treating the molten metal with magnesium. He inadvertently found when looking at a specimen under a microscope, that the graphite instead of forming a flake was present as a perfect round nodule, which eliminated almost all of the ill effects of flake graphite. This started the greatest advance in improvement of cast irons in a hundred years! In all fairness we must tell the student of the incredible coincidence that occurred at the same time. In England, at the same time, a Dr. Morrows discovered that the same thing occurred with the use Cerium, but unfortunately the use of magnesium proved to be more efficient and prevailed! The poor guy, while recognizing that he had to play second fiddle to Keith Millis, he accepted his role with the grace of an Englishman! Getting back to the metallurgical aspects, and to help the student in being aware of the significance of this discovery we will put photomicrographs of ductile (nodular) iron on the screen, "as cast and annealed". file:///c /WEBSHARE/062013/magazine/2001_3/basic.htm[6/19/ :21:23 AM]

45 The Ductile Iron News - Basic Metallurgy As Cast Annealed Here we have a metal that combines the properties of both gray irons and steels! The international Nickel Company licensed it, but the patents have run out. This means that everyone today that wishes can try to produce the metal! The problem is that the production of ductile iron requires careful control! The only policing today, is the Ductile Iron Society, but that means that the producer must belong to the society in order to participate. This is a relatively new metal and there is still much to be learned about its production. As this primer on metallurgy is not designed to show how the metal is made, we can only give precautions on what to look out for and some of the benefits. 1. Ductile iron is a very versatile metal that has replaced steel and malleable iron in great many applications. There were many instances where a design remained on the drawing board because the part was too thin to be cast in steel. Ductile iron has both the castability of gray iron and the strength of steel. The same equipment that gray iron producer's use, produces it! No wonder every producer of gray iron wanted to get in the act! There were problems! 2. The large automotive and agricultural equipment foundries have metallurgists and laboratories to control quality. This luxury is not affordable in many small foundries, but is absolutely necessary to control the production of ductile iron! There are no shortcuts! Today there are many small foundries that that invested in the equipment necessary to produce the metal. Make sure your supplier is one of these! 3. As ductile iron is one leading metal in the casting industry we are quite sure that the majority of our students recognized the name and use it. There is no way of knowing by looking at a casting whether or not it's made of ductile as against gray cast iron. The student can take this first instance of connecting the dots! Do you remember way back when we discussed damping properties and how gray iron damped out the energy because of the occurrence of flake graphite? Hit the part with a hammer dummy! If it doesn't ring, it's not ductile! If it does ring it is ductile! Gosh! Will you ever learn? 4. Ask for a certificate of compliance, if it's a very important job that needs certification. Here's the difference! In a certificate of compliance you're asking the foundry to use the same controls that they use for all customers. It should cost you nothing! If you ask for a certification it means that the foundry must pour a test bar out of the same ladle of metal that was used for your part. That test bar follows the casting through any heat treating procedures and is tested to see that it is in compliance. That will cost you and arm and a leg! So, put it in the price of the product! 5. The various grades of ductile iron can be changed from one to the other by heat treating, which we will discuss later. The various grades of ductile iron listed by ASTM A536 will be described. The first two numbers indicate the tensile strength The second two numbers indicate the yield strength The third two numbers indicate the amount of elongation We are losing sight of the fact that we are studying the action of the atoms, which, if understood, will help the student solve problems much easier. Let's get back to how the atoms react in forming nodular graphite We know from our studies that file:///c /WEBSHARE/062013/magazine/2001_3/basic.htm[6/19/ :21:23 AM]

46 The Ductile Iron News - Basic Metallurgy nature in its wisdom will always forms components in a minimum surface area per volume if unhindered! For example, take your dirty automobile hood. When it rains, the dirt offers resistance to the water doing its thing, however whenever the car is waxed the resistance is lessened and the water is able to ball up offering a minimum area per volume. We can offer many other examples, however we're quite sure you get the point! In ductile iron the graphite acts exactly the same way. The student will remember in gray irons that the metal solidifies at the same temperature the graphite precipitates and is called the eutectic. In ductile irons there is no true eutectic. There is a great deal of research still going on as to how the nodule forms but let's use a little common sense to figure out what happens according to the laws of nature. Let the Egghead's continue their research, we will describe it our way! (Wasn't there a song by that title?) Let's make some dots to connect! A. We know the graphite forms in a perfect round ball. B. We know that the metal forms dendrites when solidifying. C. We know that the if the graphite came out at the same time, they would be squashed between the branches. D. The conclusion must be, that the graphite had to precipitate while the metal was liquid and offered no resistance to the graphite following natures law and forming a minimum surface area per volume, which is a round ball! The author has proved this point by pouring ductile iron into water and examining the metal under a microscope. To no surprise, at high magnification tiny round balls were seen. In follow-up research, we isolated normal nodules by cold leaching in acid and thought that we had isolated pure graphite. We were wrong! A stupid very pretty little girl, working in the lab screwed up the experiment by picking up the whole mess with a magnet! Eventually we came to a conclusion that without any interference from dendrites, the open roses we speak of closed into the bud, capturing iron atoms between its petals! Cool! I fired her. (Just kidding!) Because graphite is present in ductile iron and because nature favors the formation of graphite, the reaction of the carbon atom is the same as in all gray irons. The metal is subject to time and temperature. If the metal is cooled slowly from austenite the iron carbide close to the graphite nodule will break down and a carbon atom will migrate to," mother graphite", because it now has a home to go to! The slower the cooling the more pearlite will be broken down to its components of iron and carbon. The carbon atom will then migrate to the nearest nodule as secondary graphite on to the prime. This is why in the photomicrograph of, "as cast", ductile iron, it shows a bulls eye structure of ferrite around the nodule of graphite. There are many ways that cast irons can cool slower from austenite. One way involves the method of heat-treating. However, more important to be understood now, is that the section of the casting will dictate the rate of cooling. The heavier the part, the longer it will take to cool and the more ferrite will form. This applies to any ferrous casting that contains an appreciable amount of silicon. The student may think we're being redundant, but this is necessary if you are going to understand heat treating, especially what may happen during normalizing. So stay with us! This is a cram course! We must do it our way. We will discuss what happens in the heat treating of cast irons later, For now we want the student to relate the action of the atoms, especially the action of the carbon. Please take some time to think deeply of the action, always thinking that the atoms are going to obey natures law, given the time and temperature! We are now going to prepare the student to the introduction of compacted graphite iron, which is part of the ductile iron group. We will explain why. Research indicated to us, right or wrong, that graphite nodules formed in the liquid, because when treated with magnesium the metal was out of equilibrium with oxygen. What seems to prove this point is that, if the ductile iron after treatment, is not file:///c /WEBSHARE/062013/magazine/2001_3/basic.htm[6/19/ :21:23 AM]

47 The Ductile Iron News - Basic Metallurgy poured within a certain time the whole mess reverts back to gray iron containing flake graphite. The student is asked to remember this fact because it will help to understand the next grade of metal, which we discuss. Is called... Compacted graphite iron This grade of cast iron is also referred to as vermicular graphite or semi ductile cast iron. It's kind of funny how this grade was developed. It's the first time we have ever heard of doing something wrong, to do it right! This grade came about by not treating the metal properly to make ductile iron. There was either not enough magnesium added or waited too long to pour the metal. In any event the resulting metal contains graphite that appears as clusters that are interconnected between the dendritic branches along with a few nodules here and there but no classical flake graphite. Let's see the difference. Compacted Graphite This is the photomicrograph of compacted graphite. Notice it is neither a round nodule nor flake. It is between the two! This metal is difficult to control because what has to occur is akin to making a deliberate mistake in producing ductile iron. Eventually it was learned that the control of this unconventional type of graphite was to deliberately add impurities to retard or hold back the formation of nodular graphite! So you see why we say that this metal was developed by doing something wrong, to make something right! What resulted was a grade of metal spawned from ductile iron that became a very useful metal that has taken its place among the rest of the cast iron family. The student will remember that the only difference between properties of cast iron with compacted, nodular, or flake graphite is the shape and distribution of graphite. The production of compacted graphite requires very careful control because it is sensitive to many factors! If the student has absorbed the information so far in our studies, the whole process of the production of cast irons will become very clear, but only if the change in relationship of the carbon atom with the element iron, in the presence of silicon, is understood. Remember, with graphite present the carbon atom has a home to go to and the choice is dependent upon time and temperature! Please slow down and connect the dots! We know that the matrix of cast irons is the same as that of steels. We know how to strengthen the matrix by controlling the amount of Pearlite present and we will learn how to enhance the strength further by heat treatment. That is the positive part of our story in as much as strength is concerned. The negative end is to what level the shape and distribution of graphite affects the matrix. If the student recognizes the distinction between the occurrence of the three types of graphite, it will be apparent that the properties of a compacted graphite cast iron is in between that of flake iron and nodular iron! All of the literature indicates that the biggest advantage of compact graphite is in its heat conductivity. The metal is relatively new and to our mind has not been fully developed as yet. We have covered, very superficially, malleable irons, gray cast irons, ductile irons, and compacted graphite irons. We will address these metals later in the section on heat treating, but right now it's time for a review of the properties and the possible uses for each category of cast irons. 1. Gray iron is the most economical of the cast irons and should be used wherever the superior properties of the other cast irons are not required. We report, you decide! 2. While ductile iron has replaced malleable iron in many cases, malleable iron is still preferred in very thin castings requiring impact resistance combined with strength. 3. Ductile (nodular iron) can, and has replaced steel in many cases. It is up to the design engineer to evaluate the properties of ductile iron to see if it fits a particular application. Ductile iron, because of its castability combined with superior properties can be used to replace gray iron enabling the design engineer to reduce the section and hence weight. We report you decide file:///c /WEBSHARE/062013/magazine/2001_3/basic.htm[6/19/ :21:23 AM]

48 The Ductile Iron News - Basic Metallurgy 4. Compacted graphite is used mostly to produce ingot molds because of the high heat conductivity. Design engineers discovering this superior property have started to use it in automotive parts that are subjected to heat. This is a relatively new material and remains for the imagination of the design engineer to find other applications. If heat is not a problem we see no particular use for compacted graphite, but we could be wrong! Wow! What am I saying! I better go see a shrink! Well, that's it. Let's start on basic heat treatment. View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

49 The Ductile Iron News - FEF Article To Promote the production and application of ductile iron castings Issue 3, 2001 FEF College Industry Conference FOR IMMEDIATE RELEASE NOVEMBER, 2001 FEF COLLEGE INDUSTRY CONFERENCE A total of 368 people-250 industry and university people attended this year's conference, along with 118 student delegates representing FEF's 32 schools. This unique conference brought together top industry executives, FEF Board Members, Key Professors, university officials and top student delegates-all interested in metal casting. Conner Warren of Citation Corp. was the conference chairman. The FEF Annual Banquet was held at the 95th Floor Signature Room restaurant in the John Hancock Building in Chicago on Thursday night, November 8. Several awards were presented including FEF's highest award, the E.J. Walsh Award. This award went to Dean Lifetime Patron, Jack Bodine, retired from Bodine Aluminum. Also receiving special recognition were- Foundry of the year presented to Waupaca Foundry in Waupaca, Wisconsin; Supplier of the year went to Hickman, Williams & Co. in Livonia, Michigan; and Society/Association of the year was the AFS-Texas Chapter. Bob Smillie of Nemak was the Master of Ceremonies. During the General Session on Friday, the Keynote address was given by Rick Sommer, President & CEO of Citation Corp. This year's three panelists included Mike Zeno, Product Development Specialist at Foseco, Inc., Cleveland, OH and an FEF scholar from Kent State; Kai Spande, GM Powertrain. Engineering Superintendent, Defiance, OH and an FEF scholar from the University of Northern Iowa; and Perry Harvey, President of Gray Syracuse-Esco, Chittenango, NY and an FEF scholar from the University of Wisconsin-Madison. During the Edward C. Hoenicke Memorial Luncheon, the AFS/FEF Combined Board Award of $6000 was given to former FEF Key Professor, Von Richards currently serving as the Robert V. Wolf Professor of Metals Casting at the University of Missouri-Rolla. Also given out this year, were 3 gifts, each in the amount of $10,000, from the recently established FEF/Ray Win Gift Program. These gifts were presented to Mike Dragomier from Kent State University, Craig Johnson from Central Washington University, and Shu-Zu Lu from Michigan Tech. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, The Industry Information Session offered students an up-close and personal look at the industry. It also gave the 33 participating companies, who had 34 tables, the most cost-effective way to see some of the top metal casting students in the country all in one place. The Awards and Recognition Breakfast speaker was the President of Central Washington University, Jerilyn McIntyre. Following her comments, 19 sponsored scholarships were awarded to the student delegates who had submitted applications for these awards (see reverse side). In addition, one school had students in the "runner-up" category. These students will each receive an expense-paid trip to the AFS Government Affairs Conference in April, Also highlighted were the four Keith Millis scholarships in Ductile Iron and the Ron Ruddle graduate level scholarship. Bill Sorensen, FEF's Executive Director, announces that next year's College Industry Conference will be in Chicago on November 7-9, More information on this conference, or any of the FEF activities, can be obtained from the FEF office at 484 E. Northwest Highway, Des Plaines, IL 60016, Phone 847/ , Fax 847/ , info@fefoffice.org, Web Page CIC Breakfast Awards, November 10, 2001 Keith D. Millis Scholarship Matthew Berndt U. of Wisconsin-Madison Keith D. Millis Scholarship Chad Moder U. of Wisconsin-Platteville Keith D. Millis Scholarship Jay Morrison Western Michigan U.

50 Keith D. Millis Scholarship Michael Taylor Tri-State Univ. Lazaro Ron Ruddle Memorial Scholarship Beltran-Sanchez U. of Alabama CISA Scholarship James Sturgeon Tri-State Univ. Richard Frazier Scholarship Sarah Obermayer Tri-State Univ. AFS Southwestern Ohio Scholarship Vincent Kerchenski Ohio State William M. Grimes Schol.-Gartland Fdry. Joshua Crites Purdue-West Lafayette Booth-Geo. W. Mathews Jr. Endowment Trisha Miller Michigan Tech Sanders-Geo. W. Mathews Jr. Endowment Laura Rowland U. of Michigan Witt-Geo. W. Mathews Jr. Endowment Dave French U. of Michigan James P. & Katherine Keating Scholarship Charles Keim U. of Missouri-Rolla Ron & Glenn Birtwistle Mem. Scholarship Brian Hartbarger Tennessee Tech Ron & Glenn Birtwistle Mem. Scholarship Elizabeth Coleman U. of Alabama Tony & Elda Dorfmueller Scholarship Charles Monroe Penn State Wm. E. Conway Schol.-Fairmount Minerals William Strecker Pittsburg State Deere Scholarship-Environmental Salvatore Zagarella Penn State Robert W. Reesman Mem. Scholarship Candice Kent Mohawk College Burleigh Jacobs Scholarship-Grede Mark Palmer U. of Wisconsin-Platteville Donald G. Brunner Scholarship-Waupaca Nathan Wischnewski Univ. of Wisconsin- Platteville George Isaac Scholarship ulian Ibarra Cal Poly-Pomona Modern Casting Partners Scholarship Sean McNerney Kent State Robert V. Wolf Mem. Scholarship Brandon Durham U. of Missouri-Rolla Runners-up (AFS Government Affairs Trip) Timothy Dues Tri-State University Douglas Harper Tri-State University Special Mention Jack H. Thompson Memorial Scholarship Charles Keim Univ. of Missouri-Rolla David Laine Scholarships Eric Armbruster Western Michigan " " Timothy Dues Tri-State University " " Allison Arndt Wisconsin-Madison " " Matthew Pettus Tri-State University " " Alicia Cobb Univ. of Missouri-Rolla " " Grant Wesson Univ. of Northern Iowa Affiliate Scholarship Ginger Connin Tri-State University View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440)

51 The Ductile Iron News - Superior Graphite Profile To Promote the production and application of ductile iron castings Issue 3, 2001 Associate Member Profile Superior Graphite Co.'s Russellville ARK Plant has been selected by INDUSTRYWEEK, the leading manufacturing management magazine, as a winning facility in the publication's 12th annual Best Plants competition. A 'Meat-and-Potatoes' Operation THE WORK IS HOT, DIRTY, AND PHYSICALLY demanding. That in a nutshell describes the conditions under which most of the 113 employees labor at Superior Graphite Co.'s Russellville, Ark., facility. They're engaged in the manufacture of synthetic graphite electrodes used primarily in electric arc furnaces at foundries and small steel mills. The process to manufacture these electrodes--each of which can weigh from 200 lb. to 1,100 lb. and measure four to six feet in length--requires extreme temperatures, up to 3,000 C to complete the conversion of carbon to graphite. On a sultry August afternoon in Arkansas no amount of insulation can fully contain the heat generated by the graphitizing furnaces. And no matter the attention paid to housekeeping, the manufacturing process blackens workers' clothes and smudges exposed skin. "It's not a job for everybody," admits plant manager Steve Condley, a 16-year veteran of Superior Graphite's Russellville operation and plant manager for the last 10. And in truth, the picture at Russellville is that of heavy industry at its most basic. "It's a meat-and-potatoes operation," adds Condley. Yet it is "highly technical in its own way," asserts production/maintenance manager John Church. Condley is also matter-of-fact in his observations about the management philosophies that guide the plant's growth and improvement initiatives. It's a straightshooting attitude he shares with Scott Anderson, assistant vice president of production for the corporate entity and also a 16-year veteran of the Russellville plant. Until last year, Anderson shared plant manager duties with Condley. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, The demanding nature of the work for Superior Graphite employees such as machine operator Greg Leopard (right) only emphasizes the need for strong safety measures, believes Chad Edelen, quality/technical manager (above). For example, on management philosophy: "Treat everyone like you'd want to be treated, and don't ask them to do anything you wouldn't do," says Condley. On lean manufacturing: "Is it lean manufacturing or is it common sense?" asks Anderson rhetorically. "[Lean is] another word for efficient operations." In truth, while Superior Graphite's Russellville plant appears to be the antithesis of "new manufacturing," it extends to its workers many leading-edge employee benefits, including gainsharing, profit sharing, and an education assistance program. It is particularly proud of its safety initiatives, however, which are extensive. "We take a four-pronged approach to safety," says quality/technical manager Chad Edelen. Those prongs include a safety committee, which manages overall safety throughout the facility; a fire brigade, which addresses fire safety and training issues; a "first responders" team, which is the first line of response to accidents in the facility; and a behavior-based safety program. Introduced in 1998, the behavior-based initiative is the most recent addition to Superior Graphite's safety program. Approximately 20 employees currently make up the S.T.A.R. (Striving Toward Accident Reduction) observer group. Each has file:///c /WEBSHARE/062013/magazine/2001_3/assocprofile.htm[6/19/ :21:33 AM]

52 The Ductile Iron News - Superior Graphite Profile received 20 hours of observer training, and their aim is to encourage safe behavior. HOW DOES THE PROGRAM WORK? A trained worker simply asks an employee for permission to observe him at work for approximately 10 minutes, looking for behaviors that are safe or "at risk," and noting any hazards in the area. The observer then provides feedback to the employee on both good and not-so-good safety behaviors. Edelen notes that an employee may be using poor safety practices unwittingly or may have been taught the wrong way. "[The] observers are the tool that brings their behaviors to their attention," he says. The plant's goal is for each safety observer to conduct eight observations a month. With that many, employees are likely to be observed on numerous occasions. Those repeatedly exhibiting at-risk behaviors are likely to start using the right procedures if for no other reason than to avoid hearing it yet again from an observer, Edelen notes. The S.T.A.R. observer group is a completely voluntary effort; employees have no incentive to participate except for the obvious one. Says 13-year employee Johnny Molloy, lab technician and chairman of the S.T.A.R. committee: "We're just trying to make [Superior Graphite] a better place to work." Superior Graphite also conducts at least two full-plant evacuation drills per year, in which scenarios for emergency situations are played out to maintain a state of readiness. Earlier this year, for example, the plant conducted a drill in which a medical emergency was declared and a furnace cave-in was reported. While management and the local authorities were aware that the exercise was a drill rather than a real event, employees were not. (However, management lurked near the furnace operators to prevent them from actually shutting down a furnace, as procedures would normally require.) Every drill teaches a lesson, and this effort was no exception. The fire brigade and first responders unit performed perfectly, says Edelen. But not everything went smoothly. For example, the fire brigade discovered it needed additional hose to reach an inaccessible area. Additionally, not all employees reported to the proper location in the parking lot as called for by evacuation instructions. The safety improvements implemented as a result of the plant's initiatives are numerous: New electrode stacking procedures have been written; the material safety data sheets (MSDS) database was rebuilt and database training initiated; new exit signs were installed around the plant. The list isn't endless, but it is extensive. And as a result of its ongoing safety measures Superior Graphite's Russellville plant has reduced its workers' compensation costs by 12.19% in the last five years and reduced its OSHA-reportable incident rate by nearly 83% in that same time frame. The plant had no OSHA reportable lost workdays in the most recent calendar year. At a Glance Superior Graphite says it extends an equally impressive level of care to its customers. In addition to responding immediately to customer questions or complaints, the Russellville plant has a number of trained personnel who make onsite visits to conduct training on graphite consumption and arc furnaces. Plant personnel "assist [customers] in whatever capacity [is] needed. Sometimes that could include doing training for them on the operation of their own furnaces, or [it] could be something as minor as packaging modifications," notes Superior Finished-product firstpass yield for finished synthetic graphite electrodes is 94.94%. Energy consumption per unit of production has decreased 29.24% in the last five years. Productivity as annual sales per employee has increased 23.4% in last five years. Days of total inventory file:///c /WEBSHARE/062013/magazine/2001_3/assocprofile.htm[6/19/ :21:33 AM]

53 The Ductile Iron News - Superior Graphite Profile Graphite in its Best Plants application. has decreased 25.2% in For example, Superior Graphite shared its safety the last five years. expertise with an Iowa customer during a visit to assist with a furnace issue unrelated to Superior Graphite electrode performance. As a result of the communication the customer built racks that ensured the heavy electrodes could not roll and potentially cause injury. Also, Superior Graphite advised the plant on methods to reduce back injuries. It makes sense, says Edelen, for a company to take such steps to assist its customers. "If we can help [our customer] be a better steel company that helps ensure their long-teen life, which ensures our long-term life," he explains. The on-site service comes at no cost to customers, despite the fact that nearly half of Superior Graphite's shipments are to markets outside the U.S. "Service is certainly more of a challenge because of logistics, but we do it," says Anderson. "The service is the edge we have." Or maybe it's simply Superior Graphite extending to its customers the philosophy it shares within its own four walls: "Treat everyone like you'd want to be treated." View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

54 Ductile Iron News - News Briefs To Promote the production and application of ductile iron castings Issue 3, 2001 MEETINGS News Briefs The next Research Committee Meeting will be held on January 8-9, 2002 at the Ramada O'Hare in Rosemont, Illinois. The June 2002 meeting has not been scheduled yet. The World ADI Conference will be held on September 25-27, 2002 at the Galt Hotel in Louisville, Kentucky. The June 2003 meeting has not been scheduled yet. There will be a Keith Millis Symposium on October 20-23, 2003 at the Crowne Plaza Resort in Hilton Head Island, South Carolina. BUSINESS On August 16, 2001, Washington Mills concluded the purchase of Exolon. Included in the purchase are the Exolon-ESK Silicon Carbide furnace plant at Hennepin, Illinois; the aluminum oxide crude ore plant at Thorold, Ontario; and the processing plant for aluminum oxide and silicon carbide at Tonawanda, New York. Included also in the acquisition is Exolon's 50% ownership in Orkla Exolon. FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, This acquisition will strengthen Washington Mills, provide a broader product line and new sales opportunities. Exolon will continue to operate as a wholly-owned subsidiary of Washington Mills. In addition, Ramsey Saab has been appointed as Manager, Metallurgical Products. This includes the sales and marketing of Carbolon MA and other silicon carbide products produced at the Hennepin, Illinois facility. Foundry Products Division of Ashland Specialty Chemical Company Introduces ZIP-CLEAN TM 38 Metal Cleaner for Cold Box Processing Dublin, Ohio (USA)--The Foundry Products Division of Ashland Specialty Chemical Company has developed and introduced ZIP- CLEAN TM 38, an environmentally friendly but fast-acting cleaner for removing high-performance cold box resin films and release agents that guild up in metal core boxes and/or tooling. Equally effective in cleaning all resins systems, Ashland's new metal cleaner product is available in 5-gallon pails and 55-gallon drums. ZIP-CLEAN 38 metal cleaner is specially formulated to minimize skin irritation; it contains no chlorinated or fluorocarbon solvents. In addition, despite its low toxicity, ZIP-CLEAN 38 features fast

55 wicking action that enables foundries to reduce downtime during cleaning operations. Jim Elwood, product manager for ZIP-CLEAN 38, explained that the cleaner should be sprayed or brushed directly onto the built-up residues of cold box tooling or patterns. "While standard metal cleaners are allowed to soak for at least 15 minutes, ZIP-CLEAN 38 works in half the time, and the softened films then can be easily removed," Elwood said. He added that small parts can be immersed and soaked in the cleaner for treatment. Ashland Foundry Products Division's U.S. Plants Receive ISO Certification Dublin, Ohio (USA) - The two U.S. manufacturing facilities of Ashland Specialty Chemical Company's Foundry products Division in Cleveland, Ohio, have been certified to ISO 14001, an international standard for environmental management systems. Ashland is the first North American manufacturer of foundry binders and resin coatings to achieve this distinction. In addition, it reached the ISO standard well in advance of global auto manufacturers' stated deadlines for industry suppliers to comply with such a standard. DaimlerChrysler, Ford and General Motors have set deadlines ranging from year-end 2001 to July 1, ISO certification required an independent assessment that these Ashland manufacturing plants established and maintain a structured approach to control the environmental impact of their processes, and that the facilities' environmental objectives and targets are being effectively achieved as part of a continuous improvement process. The British Standards Institute is the registrar body that performed the assessment. Waupaca foundry, Inc., Waupaca, WI, and Webb Wheel Products, Inc., Cullman, AL, designed a new compacted graphite iron (CGI) brake drum at a reduced weight and enhanced durability. PEOPLE Milwaukee, Wisconsin -- Grede Foundries, Inc., has named Kristin Z. Reilly Vice President and Chief Financial Officer of Grede Foundries, Inc. Milwaukee, Wisconsin - Grede Foundries, Inc., has named Jeff Friday as the Works Manager of its Liberty foundry in Milwaukee, Wisconsin. Friday received a B.S. in Technology Education from the University of Wisconsin-Stout. He joined Grede in 1992 at its Reedsburg foundry in Reedsburg, Wisconsin. In 1998, he was promoted to Factory Manager at its Greenwood foundry in Greenwood, South Carolina. Most recently, he served as Factory Manager at its Milwaukee Steel foundry in Milwaukee, Wisconsin. Grede Foundries operates foundries in the U.S. and the U.K., and is a recognized leading producer of high quality castings in gray iron, ductile iron, and steel. file:///c /WEBSHARE/062013/magazine/2001_3/nbriefs.htm[6/19/ :21:33 AM]

56 Ductile Iron News - News Briefs Julia Darlow elected to Intermet Board of Directors Troy, Mich., October 11, Intermet Corporation (Nasdaq: INMT) today announced the election of Julia D. Darlow to its Board of Directors, effective immediately. Darlow is a senior member in the law firm of Detroit-based Dickinson Wright PLLC. Her areas of practice include domestic and international business transactions, joint ventures, and mergers and acquisitions, and she has served as a member of the firm's governing board. Recently, Darlow has been on leave from the firm as a loaned executive to the Detroit Medical Center in the position of Senior Vice President. "We are very pleased to have Julia join our board," said Doddridge. "She is familiar with INTERMET having provided assistance and advice to the company in the past. Her expertise will prove valuable to the company as we go forward with our strategy of becoming the world's leading supplier of cast-metal automotive components." Milwaukee, Wisconsin -- Grede Foundries, Inc., has named Peter E. Sohlden Executive Vice President and Chief Operating Officer of Grede Foundries, Inc. Sohlden received a Bachelor's Degree in Metallurgy in 1965 from Michigan Technological University and a Master's Degree in Metallurgical Engineering from the University of Wisconsin-Madison in He joined Grede in 1969 at its Liberty foundry in Milwaukee, Wisconsin. Since then he has held several positions within Grede, most recently Vice President of Operations. Miller and Co., LLC, Rosemont, IL, appointed H. Fred Linebarger director of technology. Back to top View Ductile Iron Related Publications Located in Strongsville, Ohio, USA Pearl Road, Suite 234; Strongsville,Ohio Billing Address: 2802 Fisher Road, Columbus, Ohio Phone (440) ; Fax (440) jwood@ductile.org

57 The Ductile Iron News - Xarifa Bean To Promote the production and application of ductile iron castings Issue 3, 2001 Company. OBITUARY Xarifa Sallume Bean, One of the most active foundries in the charter of the Ductile Iron Society was Morris Bean & Company. The signature of William Beatty, one-time Morris Bean & Company President, appears on the Articles of Incorporation, signed in June of At Morris Bean, the technical research and development was headed by Xarifa Bean for over 39 years. Many of you will remember her dedication to the ductile iron industry and the Society. We are sad to report that Xarifa passed away in September of this year and the following obituary was submitted by Morris Bean & Xarifa Sallume Bean, 91, former Chairman, CEO and Co-founder, with her husband Morris, of Morris Bean & Company, Yellow Springs, Ohio. Her commitment to Morris Bean & Company, and the industry, began in 1931 upon her graduation from Antioch College, Yellow Springs, Ohio. She continued her active involvement with Morris Bean & Company for over seventy years until shortly before her death on September 25, For over 39 years Mrs. Bean headed the company's technical research and development efforts. She held six patents for foundry processes, including groundbreaking developments in resin bonded sand. In recognition of her many contributions to the industry she was selected as a Charter Inductee of the Foundry Management and Technology Hall of Honor in Over the years Mrs. Bean received many honors and awards from the foundry industry and the community in which she lived. For more information about Mrs. Bean's life and career go to the news section of MorrisBean.com XARIFA SALLUME BEAN FEATURES Cover Story - DIS Visits Neenah Foundry at 115th T&O Meeting DIS Operating Committee Meeting Simulation of Microstructure and Mechanical Properties in Ductile Iron Offsetting Macro-Shrinkage in Ductile Iron Near Net Shape Ductile Iron Components - A Novel Approach Using Semi-Solid Forming Shrinkage in Nodular Iron Solving Casting Problems Basic Metallurgy FEF College Industry Conference DEPARTMENTS Associate Member Profile Superior Graphite - Best Plant News Briefs Obituary Xarifa Sallume Bean, Xarifa Sallume Bean, one of the founding group of Morris Bean & Company of Yellow Springs, Ohio, died at her home, Tuesday, September 25. She was 91 years of age. Born October 3, 1909, in Salem, Columbiana County, Ohio, she was the daughter of Louise and Shibly Sallume. She was named Zareepha Louise Sallume, after the sister of her Syrian father. She and her brother, David Sallume, spent their childhood with her mother's family in Palo and Battle Creek, Michigan, until she came to Yellow Springs in 1926 to attend Antioch College. The day after receiving her bachelor's degree in mathematics from Antioch in 1931, Xarifa married Morris Bean, thus beginning her lifelong commitment to her work and family. Morris had graduated from the college the year before and was managing what was then the Antioch Art Foundry, one of Antioch's student industries established by Arthur Morgan in the mid-1920s. The foundry was engaged in casting art objects and architectural sculptures in bronze. A pioneer in the foundry industry, first as a woman, and then in research, design and corporate leadership, Xarifa spent 39 years as head of the company's technical research and development team. She held six patents for foundry processes, including a process for resin-bonded sands that is still used in aluminum and other metal casting that requires extreme precision of parts. Before WWII the foundry had been purchased by General Motors. In 1946, Morris, Xarifa and a group of associates purchased the business, selected Morris Bean as president, and formed Morris Bean & Company. By then the company had begun expanding its technical achievements to the production of highly engineered castings for the industrial market. file:///c /WEBSHARE/062013/magazine/2001_3/beanobit.htm[6/19/ :21:24 AM]