HIGH PERFORMANCE DIE CASTING ALLOYS -Castings for Improved Readiness-

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1 HIGH PERFORMANCE DIE CASTING ALLOYS Castings for Improved Readiness Advanced Casting Research Center (ACRC) Metal Processing Institute (MPI) WPI L. Wang, D. Apelian, M.M. Makhlouf ACRC WINTER MEETING December 56, 27

2 Background Project part of AMC s Casting for Improved Readiness (CIR) Program, sponsored by the Defense Supply Center, Defense Logistics Agency (DLC). Objective of CIR is to improve quality, reduce costs, and cut lead times during procurement. Project focused on alloy selection. Two phases: Phase I developed an electronic tool, iselectal, for selecting alloys. The current work is Phase II Develop optimum premium grade alloys.

3 Objective Develop a set of select or premium grade alloys that are optimized for specific properties in order to manufacture costeffective cast products. Chemistry limits in alloy specification are wide resulting in wide variations in mechanical properties noncompliance issues Need to reduce variation in properties in cast components to enable casting conversions and meet demands Need for premium grade high performance alloys

4 Tasks Based on DLA requirements the tasks are: 1. Determine target applications/alloy to be optimized; discuss with industry colleagues/partners. 2. Use iselect to optimize alloy(s) for the specified application. 3. Cast samples of the select grade (premium grade) alloy laboratory trials. 4. Validate the above select grade alloy(s) at industrial beta sites on commercial die cast components. 5. Develop of the select grade die cast alloy(s). 6. Disseminate Technology Transfer of the results.

5 Progress Task 1 Partners, Target Components, & requirements: Partners: Contech (formerly SPX) Premier Tool & Die Cast Requirements improve mechanical properties Target components army vehicles Task 2 Select Target Alloys: Three alloys selected: AMC 38*, AMC 145*, and AMC 145 Task 3 Lab Trials: Defining target alloy compositions Microstructural analyses Tensile property tests Evaluating the target alloys Task 4 Industrial Beta Site Tests: In progress

6 Target Alloy Selection AMC 38* chemistry within limits of currently used Al die casting alloys, selected mainly by using iselect. AMC 145* and AMC 145 new AlSiCuMgFeMn system alloys, selected based on iselect and knowledge from recent alloy development work, with these considerations: Si provides strengths and good castability. Higher Si (>9%) refines and disperses intermetallic particles, improving ductility. Cu is the major strengthening element. Fe alleviates die soldering but reduces ductility. Mn can alleviate die soldering and alter the unfavorable morphology of Fe compounds, improving ductility. Two new Al die casting alloys, Silafont36 and Castasil37 contain.13.15% Fe, and.4.8% Mn and possess high ductility (up to 18 2%). Our work showed: Mg from.5 to.5% increased TS and YS significantly in 38 with little ductility decrease; Mg at 24% refines the eutectic structure, alters the β(al,si,fe) phase morphology and enhances properties.

7 Lab Trials Define target alloy compositions Microstructural analyses of 7 sets of 38 alloys with various levels of Si, Mg, Cu, Fe, and Mn 9 alloys for mechanical property tests chosen based on resultant microstructures Evaluating the target alloys compared with reference (commercial A38 and A356) alloys Tensile property tests Microstructural analyses

8 Mechanical Property Tests Standard tensile test specimens were produced in permanent mold, minimum of 3 pieces for each alloy. All alloys were produced under the same conditions: degassed for 4 minutes, poured at ~75 C etc. Some alloys have strong aging phenomena and so all the alloys were tested at 1, 1, 3 days after cast, 35 bars tested each time.

9 Alloy Compositions Used in Defining Target Alloys # # # # # # # # #1 Sr Ti Ni Zn Mn Fe Cu Mg Si Composition (%) Alloy

10 Mechanical Properties Measured in Tests for Defining Target Alloys Alloy #1 #2 #3 #4 #5 #6 #7 #8 #9 TS (Ksi) YS (.2%, Ksi) e (%) 1day 1days >3days 1day 1days >3days 1day 1days >3days 32.8± ± ± ± ±3.1 1.± ± ± ± ± ± ±.2 23.± ± ± ± ± ± ± ± ± ± ± ± ±2.9 3.± ± ± ± ± ± ± ± ± ± ± ±1. 15.± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±.4.92±.3.71±.8.76± ± ± ± ±.6.8±.13.86± ± ± ± ±.6 1.2±.12.96±.14

11 Compositions of Target and Reference Alloys Measured Measured Specified A Measured Specified A Target AMC Measured Target AMC 145* Measured.2.2 < Target AMC 38* Sr Ti Ni Zn Mn Fe Cu Mg Si Composition (%) Alloy

12 Mechanical Properties of Target and Reference Alloys Alloy AMC 38* AMC 145* AMC 145 A38 A356 Test Time (Day after Cast) 1 7 >3 1 7 >3 1 7 >3 1 7 >3 1 7 >3 UTS (Ksi) 35.7± ± ± ±.3 3.9± ± ± ±.6 33.± ± ±.6 3.9± ± ± ±1. Tensile Property YS (Ksi) 22.4± ± ± ±.4 2.8± ± ± ± ± ± ± ± ± ± ±.1 Elongation (%) 1.5± ± ± ±.7.98±.5 1.± ± ± ± ±.16.98±.16.81± ± ± ±.46

13 Typical Tensile Properties of Permanent Mold Test Bars 5 4 AMC 38* Strength (Ksi) 3 2 Commercial A38 AMC 145* Elongation (%)

14 Microstructures of Target and Reference Alloys AMC38* Commercial A38

15 Microstructures of Target and Reference Alloys AMC145* AMC145

16 Results The microstructures of all the target alloys are finer than commercial A38, especially the Ferich phases not only fewer and finer but also the morphology being less detrimental. Overall tensile properties of alloy AMC38* are much better than those of commercial A38 alloy. Thirty days after casting, TS, YS, and % of AMC38*/A38 alloys are 38.6/3.9 Ksi, 26.1/23.8 Ksi, and 1.49/.81 %; increases of about 25%, 9.7%, and 84%, respectively. The AMC145* and AMC145 alloys also show higher TS and e% but slightly lower YS.

17 Beta Test Lab trials: property tests conducted on specimens cast in permanent mold. Die casting vs permanent mold casting: cooling faster, finer microstructure and better properties. Tensile properties of A38: Condition Specification Die Cast Permanent Mold DAS (µm) TS (Ksi) ±2 3.9 YS (Ksi) ± Elongation (%) ±.7.81 Validation of target alloys at Contech and Premier Tool & Die Cast

18 Microstructural Difference Die Casting vs Permanent Mold Casting Commercial A38 alloys Die Cast Permanent Mold Cast

19 Acknowledgements AMC s PROACT program is sponsored by the Defense Supply Center Philadelphia, Philadelphia, PA, Defense Logistics Agency, Ft. Belvoir, VA. Contech Corp. Premier Tool & Die Cast ACRC Consortium Members.