WELDABILITY OF ASTM A 1010 STEEL

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Proceedings of 8 th International Conference on Short and Medium Span Bridge Niagara Falls, Canada 2010 WELDABILITY OF ASTM A 1010 STEEL Hormoz Seradj Bridge Engineering Section, Oregon Department of

This problem is more pronounced in areas with coastal weather conditions such as the State of Oregon.

1 Proceedings of 8 th International Conference on Short and Medium Span Bridge Niagara Falls, Canada 2010 WELDABILITY OF ASTM A 1010 STEEL Hormoz Seradj Bridge Engineering Section, Oregon Department of Transportation, USA ABSTRACT Corrosion of steel bridges has been an ongoing problem that requires significant expenses for upkeep and replacement. This problem is more pronounced in areas with coastal weather conditions such as the State of Oregon. The Oregon Department of Transportation has investigated the design and construction of bridges using ASTM A 1010 steel, which has a potential for reducing some of these problems. The composition of ASTM A 1010 Steel (Duracorr) includes over 11 percent chromium, making this steel more resistant to corrosion than weathering steel and HPS. The Oregon Department of Transportation became interested in ASTM A 1010 for its possible use in the construction of steel bridges. Furthermore, the State of Washington expressed an interest to use this steel when constructing bridges that are known to have a high risk for corrosion. The states of Washington and Oregon jointly funded research to determine weldability of the material. 1. INTRODUCTION Steel is a very efficient construction material. However, it has lost popularity among engineers and owners because of its tendency to corrode causing a high life cycle cost. One factor that increases this cost is the need to recoat the steel members during the design life of the bridge. Steel bridges on the Oregon coast are a drain to the State s bridge maintenance budget because they have a high life cycle cost. The McCullough Bridge in Oregon, (Fig. 1) is a good example of section loss in a steel bridge due to corrosion. Fig. 1. Section losses of the McCullough Bridge on Highway 101 in the Coos Bay, Oregon Therefore, changing the chemical composition to create a more corrosion resistive material is desirable. Weathering steel has been helpful in reducing the corrosion rate; however, it cannot be used in a harsh corrosive environment

The Federal Highway Administration recommends that weathering steel be used with caution for low water crossings with ten feet or less over stagnant sheltered water and eight feet or less over moving

This bridge has about one foot of clearance between soffit of the multi-cell box system and the channel stream (Fig. 2 a).

A plate equal to the depth of the steel cell box closes the open longitudinal side of the last cell. Design detailed plates are then added to either end of each box (Fig. 2 c).

2 The Federal Highway Administration recommends that weathering steel be used with caution for low water crossings with ten feet or less over stagnant sheltered water and eight feet or less over moving water (FHWA 1989). Colusa County, California constructed a two span multi-cell box system bridge using uncoated steel. This bridge has about one foot of clearance between soffit of the multi-cell box system and the channel stream (Fig. 2 a). Multi-cell steel box systems are composed of 8 plates that are folded into a U-shape and then welded together (Fig. 2 b). A plate equal to the depth of the steel cell box closes the open longitudinal side of the last cell. Design detailed plates are then added to either end of each box (Fig. 2 c). This type of bridge is easy to construct and heavy cranes are not required for erection of the steel boxes. (a) Fairview bridge two span continuous for live load (b) Folded U-shape single cell (c) Module of a multi-cell box system Fig. 2. Fairview Road Bridge, Colusa County, California: (a); (b); (c) ArcelorMittal USA made A 1010 steel (ASTM 2009a) available in the United States. However, it is mainly used in industrial settings as thin plates and has been used sporadically in plates with greater thickness. The first bridge application of A 1010 steel was in a multi-cell box system bridge construction with a plate thickness of 0.16 in the Fairview Road of Colusa County in the state of California. The Fairview Road Bridge was designed and constructed utilizing A 1010 steel which has superior corrosion resistance properties with respect to weathering and HPS Grade 70W or 100W. The State of Oregon became interested in evaluating efficiency, strength, and the superior corrosion resistance properties of A1010 for possible use in its steel bridges. Internal Oregon Department of Transportation studies concluded that the upper span limit for thin plates and multicell box systems is 100 (30.5 m). Fabricators were not interested in purchasing a break press because of its high price, limited use and competition with other alternate options used in very short span bridges. Another concern was the inability to inspect inside the box girders. The Oregon Department of Transportation is considering a broader use for A 1010 in bridges spanning more than 100 feet. ASTM recognizes the maximum thickness of A 1010 steel to be one inch (25 mm). A key requirement is the steel mills ability to produce an ASTM A 1010 plate that is thicker than one inch meeting ASTM A 709 (ASTM 2009b) requirements for design and construction of steel girders. 2. LITERATURE REVIEW AND PLANNING There is no prequalified welding procedure in AWS D1.5 (AWS 2008) for ASTM A Welding procedure for a one-inch-plate thickness of ASTM A 1010 steel was investigated (Kelly 2003). Their study is based on interpass temperature boundaries of 210 F to 225 F with a variation of heat input from kj/in. The fabricators of Oregon s bridges felt that this limiting heat interpass temperature affects the fabrication cost of steel girders. Therefore further studies with different welding parameters were carried out. However, the time required to fabricate a steel girder by limiting the interpass temperature to 225 F was increased. Therefore the cost of the bridge for its anticipated life cycle would increase

3 It is recommended to use Lincoln Blue Max ER309 L, 3/32 inch diameter for Submerged Arc Welding and Lincoln Blue Max 2000 Flux for fillet welding. ER309 has more than 22% Cr and more than 12% Ni. This consumable is expensive and does not require pre or post heating. Another consumable that can be employed for ASTM A 1010 is ER410NiMo, a soft martensitic electrode with 12% Cr and 4.5% Ni. ER410 is a less expensive consumable than ER309 and has a recommended pre heating of F. Lincoln Electric (2006) specifies that it also requires 1373 F preferred post heating after cooling slowly to room temperature. This process also may result in an increase in fabrication cost therefore falling short of the mill s recommendation. ISG reported an encouraging result after an extensive testing of ASTM A1010 material. The mechanical property tests were not limited to V-Notch Charpy Impacts at different temperatures (International Steel Group Inc. 2003). Based on the Nelson (Nelson Stud Welding 2005) and the ISG (Kelley 2003) reports, a welded stud on A 1010 steel meets AWS D1.5 Bridge Welding Code requirements. 3. ACTION PLAN Kelley (2003) reports extensive testing program on A 1010 steel; therefore further research on the base metal was not needed. The following investigations were performed: Groove weld (Sub merged Arc Welding process) Fillet weld single and double pass Accelerated Corrosion Test Machinability of ASTM A 1010 It was decided to first duplicate the weld prequalification tests done by ISG and evaluate the outcomes. Their prequalification tests were based on AWS D1.6 (AWS 2007) however confirmation to AWS D1.5 was necessary (Kelley 2003). The investigation could be continued when the weld sample could pass all AWS D1.5 requirements. The welding parameters for full penetration groove weld were set to 450 Amps, 34 Volts, 17 inch/minute travel and 54 kj/in heat input. Welding consumables for Submerged Arc Welding were ER309 L, 3/32 diameter. Fig 3 shows a single bevel groove weld joint detail with a ½-inch A 1010 steel backing bar to meet Section 5 of AWS D1.5 for weld qualification. Welding direction is normal to the rolling direction of the plate. Test plates were supported on six bars that were tack welded to the plates for stability (Fig. 3). 3.1 Lesson Learned from First Test The first submerged arc welding test was completed using welding parameters for full penetration and an interpass temperature of 225 F which is specified in ISG s report with no preheating. Test results from the first test samples confirmed ISG s report and supported increasing the interpass temperature to the maximum allowed in the AWS D1.5 for production purposes. The AASHTO LRFD Bridge Design Specifications (AASHTO 2007) require 25 ftlbs for steel specimens less than 2 thick with grades 36 and 50 for a fracture-critical member at (Zone 2) 40 F. Two A 1010 steel specimens were tested under these criteria and results of 71 ft-lbs and 76 ft-lbs were obtained. Two additional specimens of A 1010 steel were tested at (Zone 2) 0 F and results of 35 ft-lbs and 38 ft-lbs. These results equal or exceed the AASHTO LRFD Design Specification value for steel specimens less than 1 thick of HPS Grade 100W for a fracture-critical member at 0 F, 35 ft-lbs

(a) Single bevel groove weld detail with 25 angle (b) Test setup Fig. 3.

To shorten the cooling time a high pressure hose was used to blow air under the weld sample (Fig. 3). It took almost six hours to complete 26 inches of butt weld on a one-inch-thick plate.

To continue the welding test, the lifted part of the test sample was stabilized.

4 (a) Single bevel groove weld detail with 25 angle (b) Test setup Fig. 3. Single bevel groove weld and test set-up A significant amount of time was required to cool the specimens to a 225 F interpass temperature. To shorten the cooling time a high pressure hose was used to blow air under the weld sample (Fig. 3). It took almost six hours to complete 26 inches of butt weld on a one-inch-thick plate. During this test the A 1010 sample plate was observed to distort, resulting in the breaking of tack welds, and the separation of the plate from its support (Fig. 4 a). To continue the welding test, the lifted part of the test sample was stabilized. This observation raised the issue of distortion levels, residual stress and the need to perform comparison with conventional steel fabrication. It was decided to examine and measure distortion level of a carbon steel and ASTM A It was determined that distortion using the ER309L consumable is much greater than that which occurs when using a carbon steel consumable. Figure 4b shows distortion of carbon steel (CS-2) and ASTM A1010 steel (SS-2). (a) ASTM A1010 plate distortion during the welding (b) Distortion of carbon steel (CS-2) and A1010 steel process (SS-2) Fig: 4 Angular distortion 3.2 Additional Set of Tests The reported test results met all requirements of AWS D1.5 and indicated that there was room to increase the weld interpass temperature. The outcome of the test was sufficiently encouraging that two additional tests were run with 300 F and 400 F interpass temperatures. All test results for the 400 F interpass temperature met AWS D1.5 requirements. Test results for 300 F interpass were satisfactory except that one of the transverse tensile tests failed. When a sample fails, AWS D1.5 (AWS 2008) permits repeating the tensile test. However, no more samples were available. Therefore, it was necessary to rerun another test with interpass temperature of 300 F to determine whether this interpass temperature is satisfactory. The result of the tests was significant. According to AASHTO LRFD Bridge Design Specifications (AASHTO 121-4

$2007), the minimum V-Notch Charpy impact test result for steel specimens less than 2 thick with grades of 36 and 50 for a fracture-critical member at (Zone 2) 40 F is 25 ft-lbs.$ $Furthermore, the AASHTO LRFD Bridge Design Specifications for steel specimens less than 1 thick of HPS Grade 50W for a fracture-critical member at 0 F require 30 ft-lbs.$

5 2007), the minimum V-Notch Charpy impact test result for steel specimens less than 2 thick with grades of 36 and 50 for a fracture-critical member at (Zone 2) 40 F is 25 ft-lbs. The test results obtained were 109 ft-lbs and 83 ftlbs, almost three times the specified minimum fracture toughness. Furthermore, the AASHTO LRFD Bridge Design Specifications for steel specimens less than 1 thick of HPS Grade 50W for a fracture-critical member at 0 F require 30 ft-lbs. The results of the two specimens tested were 61 ft-lbs and 56 ft-lbs in Zone 2 and 3 which exceed this requirement. In addition another test, a 450 F interpass temperature was achieved and all test results were acceptable. (Fig. 5) (a) Charpy V-Notch impacts test results (b) Test sample of one interpass welding process Fig. 5. CVN results and specimens The fabricator reported that the transverse tensile samples exhibited a separation outside of the fracture zone not found in carbon steel tensile samples. This lamination-like defect is shown in Fig. 6. The fabricator inspected all transverse tensile samples with straight beam Ultrasonic testing and reported no indication of lamellar tearing. Fig. 6. Transverse tensile test 4. ACCELERATED CORROSION TEST The plan included an accelerated corrosion test simulating coastal service conditions that was performed in the research section of the Oregon Department of Transportation. Weathering steel and high performance steel were used as a basis for performance comparison between these steels and ASTM A Test samples were exposed to three different environments, fresh water plus drying, fresh water and salt water plus drying, and an aggressive condition of salt water and high humidity. Crevice corrosion was investigated by attaching rubber stoppers to selected specimens which were held in place with O-rings. Figure 7 shows the test set up for different environments. The performance of the test samples after two years is shown in Fig. 8. The gain and loss of the thickness of each specimen is shown in Table

All specimens (A 1010, A 588 and HPS 70W) were 1 x1.5 x2.5 plates, ground down to a surface roughness of 0.0005 inches.

Figure 7(a) shows the samples hanging in basins (two left) for fresh water spraying and the fans for drying and two right basins for fresh water and salt water plus drying.

6 All specimens (A 1010, A 588 and HPS 70W) were 1 x1.5 x2.5 plates, ground down to a surface roughness of inches. The specimens were conditioned by being sprayed with distilled water twice each week for 6 weeks prior to exposing them to the intended environmental conditions. Figure 7(a) shows the samples hanging in basins (two left) for fresh water spraying and the fans for drying and two right basins for fresh water and salt water plus drying. Figure 7(b) shows the salt spray-only samples inside the covered container (a) Samples hanging in fresh water Fig. 7: Corrosion test setup (b) Salt spray only samples 4.1 Ongoing Research The Oregon Department of Transportation decided to have a more in depth, quantifiable, study of steel corrosion. The goal of this study will be to establish a procedure for estimating the corrosion rate and performance of selected steel alloys in a given environment near the Oregon Coast. Atmospheric corrosivity will be measured using a CLIMAT test which was originally called a wire-on-bolt test. This test coupon consists of a wire wrapped around a threaded mild steel bar for creating a galvanic couple. ASTM G 116 recommends using aluminum wire to wrap around the mild steel. The coupon will be exposed to the specified corrosive environment for 90 days. Published research suggests that a marine corrosivity index (MCI) value is a good indicator of atmospheric corrosivity. Therefore a MCI value will be calculated based on the percentage of weight that the aluminum loses after 90 days of exposure of each coupon. Three sample alloys (A 588, HPS 70W and A 1010) will be exposed to the same corrosive environments specified in the CLIMAT test. These tests will be performed in accordance with ASTM G Standard Practice for Conducting Atmospheric Corrosion Test on Material (ASTM 2003). Corrosivity will be measured at 2.5, 5 and 10 years. 5. MACHINABILITY OF ASTM A 1010 A Cincinnati Bickford drill machine was used to drill holes on 1 thick ASTM A 1010 and A 572 steel, both Grade 50. The fabricator drilled 3 holes with the same feed and speed on each sample plate and reported no abnormal wear on the drill bit or on the quality of the holes. A dual commercial bandsaw was used to cut samples of 1 thick ASTM A 1010 and A 572 steels, both Grade 50. The fabricator reported that A 1010 is tougher than A 572 Grade 50 but did not cause any abnormal wear

7 A588 HPS70W A1010 A1010 Weld (a) Fresh water exposure 4/day. (b) Fresh water exposure 4/day and salt spray 2/ week. (c) Sealed container with water reservoir and salt spray 2/week. Fig 8. Samples after 2 years of exposure

8 Environment Condition Fresh water 4 times a day Fresh water 4 times a day + salt water twice a week Salt water twice a week in covered container Table 1: Corrosion test results Average Specimen Alloy Notes Surface -ve or +ve (in) A 588 A few shallow localized depressions up to 0.02" wide Flat A 1010 Many depressions up to 0.01" wide across surface possibly due to initial porosity HPS 70W Cressive Flat Cressive Flat Cressive A 588 A few shallow depressions up to 0.02" wide under the stopper No unusual corrosion under stopper. Some depressions A 1010 up to 0.02" on one side of sample due to initial porosity? 0.00 HPS 70W A few shallow depressions up to 0.03" wide outside of stopper A 588 Surface corrosion A 1010 A few shallow depressions up to 0.03" wide HPS 70W Surface corrosion A 588 Surface loss of 0.006" under the stopper. Extensive surface corrosion A 1010 Surface corrosion. One shallow depression 0.02" wide HPS 70W A few shallow depressions up to 0.03" wide outside of stopper A 588 Extensive surface corrosion A 1010 Extensive depression and pitting. Pits up to 0.09" wide HPS 70W Surface corrosion A 588 Surface loss of " under the stopper A 1010 Extensive depression and pitting primary outside stopper. Pits up to 0.09" wide HPS 70W 6. CONCLUSION Interpass temperatures ranging from 225 F to the maximum production interpass temperature of 450 F were investigated. The heat input for the submerged arc welding process was set to 55kJ. Average V-Notch Charpy impacts tests for test samples with 225 F, 300 F, 400 F and 450 F interpass temperatures exceeded AASHTO LRFD Bridge Design Specifications requirements. Side bend tests were performed according to AWS D1.5 requirements. No cracks were observed. All test samples surpassed the standard requirement set for tensile strength except for one sample at 300 F interpass temperature. However, it passed when the test was repeated. Macro and Micro metallurgical samples indicated good fusion and grain structures. The angular distortion that resulted from SAW in A 1010 is much greater than distortion resulting from SAW in ASTM A 709 Grade 50. The amount of distortion on A 1010 is almost twice the ASTM A 709 Grade 50. The distortion of A1010 can be controlled by proper welding processes. Mechanical properties of each full penetration groove weld were determined by a transverse tensile test, a side bend test, heat affected zone test and a weld metal charpy test (CVN). Also, macro and micro metallurgical examination of the weld heat affected zone, weld metal and base metal indicated that A 1010 could be used in bridge construction

9 Four A 1010 tee welded samples (fillet weld, single and two pass) were made using an automatic submerged arc and semi-automatic flux core welding process. All test samples were cut in 1 long sections per AWS D1.5 and stressed to failure. All of the samples had ductile failure and fractured in the weld. The fracture path was through the weld metal as expected. A Cincinnati Bickford drill machine was used to drill holes on 1 thick ASTM A 1010 and A 572 steel, both Grade 50. The fabricator drilled 3 holes with the same feed and speed on each sample plate and reported no abnormal wear on the drill bit or on the quality of the holes. A dual commercial bandsaw was used to cut samples of 1 thick Duracorr and ASTM A 572 steel, both Grade 50. The fabricator reported ASTM A 1010 is tougher than A 572 Grade 50 without any abnormal wear. This study supports using ASTM A 1010 steel for bridge construction in mildly salty and humid environments. It has shown to have more resistance to corrosion than weathering steel or high performance steel. 6. REFERENCES AASHTO LRFD Bridge Design Specifications, 4 th Edition with 2008 Interim Revisions. AASHTO, Washington, D.C. AWS AASHTO/AWS D1.5M/D1.5: 2008 Bridge Welding Code. American Welding Society, Miami, Florida. AWS AASHTO/AWS D1.6/1.6M: 2007 Structural Welding Code Stainless Steel. American Welding Society, Miami, Florida. American Society For Testing And Materials (ASTM). 2009a. ASTM A1010/A1010M-01 Standard Specifications for Higher-strength Martensitic Stainless Steel Plate, Sheet and Strip. ASTM International, West Conshohocken, PA. American Society For Testing And Materials (ASTM). 2009b. ASTM A 709/A7-09 M Standard Specification for Structural Steel for Bridges. ASTM International, West Conshohocken, PA. American Society For Testing And Materials (ASTM) ASTM G50-76(2003) Standard Practice for Conducting Atmospheric Corrosion Tests on Metals. ASTM International, West Conshohocken, PA. Doyle, D.P. and Wright. T.E Rapid Methods For Determining Atmospheric Corrosivity And Corrosion Resistance. John Wiley & Sons, New York, NY. Fletcher, F. B. and Christopher G New Stainless Steels for Bridge Applications. International Bridge Conference, Pittsburgh, PA. Fletcher, F. B., Ferry, B. N. And Beblo, D. G High Performance Corrosion-Resistant Structural Steel, High Performance Structural Steels, ASTM International. (is this a paper, report or book?) Fletcher, F. B., Townsend, H. E. And Wilson, A. D Corrosion Performance of Improved Weathering Steel for Bridges. World Steel Bridge Symposium, National Steel Bridge Alliance, Orlando, FL USA. Fletcher, F. B., Wilson., A. D., Strasky, J., Kilpatrick, J. N., Alcock, L. T., and Wrysinski, J. S Stainless Steel for Accelerated Bridge Construction. FHWA Accelerated Bridge Construction Conference, San Diego, CA USA. Kelley, S.C Characterization of Submerged Arc-welded 1-inch-thick Duracorr. Bethlehem Stel Corporation Research Dept., International Steel Group, Inc. Bethlehem, PA. Lincoln Electric Company Consumables, Metrode Welding Consumables, 12% Martensitic Stainless. Lincoln Electric Company, Cleveland, OH. Nelson Stud Welding Application Qualification Testing of Bethlehem Steel DURACORR Stainless Steel Base Plate Material Using Nelson Mild Steel and Stainless Steel 18-8 Studs. Nelson Stud Welding, Kenosha, WI. Federal Highway Administration Uncoated Weathering Steel in Structures, Report T5140. FHWA, U.S. Department of Transportation, Baltimore, MD

Section 906. STRUCTURAL STEEL

906.01 Section 906. STRUCTURAL STEEL 906.01. General Requirements. Finished rolled shapes must be free from imperfections that affect strength and durability in accordance with ASTM A 6. Rolled shapes