HIGH PERFORMANCE DIECASTING ALLOYS

-Castings for Improved Readiness-

Advanced Casting Research Center (ACRC)Metal Processing Institute (MPI) - WPI

L. Wang, D. Apelian, M.M. Makhlouf

ACRC WINTER MEETINGDecember 5-6, 2007

Background

• Project part of AMC’s Casting for ImprovedReadiness (CIR) Program, sponsored by theDefense 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,i-Select-Al, for selecting alloys. The current work isPhase II … Develop optimum premium grade alloys.

Objective

Develop a set of select or premium grade alloysthat are optimized for specific properties inorder to manufacture cost-effective castproducts.

Chemistry limits in alloy specification are wideresulting in wide variations in mechanical propertiesnon-compliance issues

Need to reduce variation in properties in castcomponents to enable casting conversions and meetdemands

Need for premium grade high performance alloys

Tasks

Based on DLA requirements the tasks are:

1. Determine target applications/alloy to be optimized;discuss with industry colleagues/partners.

2. Use i-select to optimize alloy(s) for the specifiedapplication.

3. Cast samples of the select grade (premium grade)alloy – laboratory trials.

4. Validate the above select grade alloy(s) at industrialbeta sites on commercial die cast components.

5. Develop of the select grade die cast alloy(s).6. Disseminate - Technology Transfer of the results.

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 380*, AMC 1045*, and

AMC 1045 Task 3 - Lab Trials:

– Defining target alloy compositionsMicrostructural analysesTensile property tests

– Evaluating the target alloys Task 4 - Industrial Beta Site Tests:

In progress

AMC 380* - chemistry within limits of currently used Al diecasting alloys, selected mainly by using i-Select.

AMC 1045* and AMC 1045 - new Al-Si-Cu-Mg-Fe-Mn systemalloys, selected based on i-Select and knowledge from recentalloy 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 ofFe compounds, improving ductility. Two new Al die castingalloys, Silafont-36 and Castasil-37 contain 0.13 - 0.15% Fe, and0.4 - 0.8% Mn and possess high ductility (up to 18 – 20%).

Our work showed: Mg from 0.05 to 0.5% increased TS and YSsignificantly in 380 with little ductility decrease; Mg at 2-4%refines the eutectic structure, alters the β(Al,Si,Fe) phasemorphology and enhances properties.

Target Alloy Selection

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 A380 and A356) alloys Tensile property tests Microstructural analyses

Lab Trials

Standard tensile test specimens were producedin permanent mold, minimum of 30 pieces foreach alloy.

All alloys were produced under the sameconditions: degassed for 40 minutes, poured at~750°C etc.

Some alloys have strong aging phenomena andso all the alloys were tested at 1, 10, 30 daysafter cast, 3-5 bars tested each time.

Mechanical Property Tests

Alloy CompositionsUsed in Defining Target Alloys

00.110.0070.0010.030.112.064.3314.4#900.120.0070.0010.030.960.044.3614.4#800.010.0030.0010.030.10.0088.9314.5#700.010.0030.0010.010.090.0082.5614.7#600.010.0030.0010.0070.090.0081.6314.5#500.010.0020.0030.0030.090.0080.4614.4#4

0.040.010.0020.0040.0010.060.0070.00212.9#300.030.020.030.040.232.144.113.5#200.0030.0030.0010.020.10.0024.215.0#1SrTiNiZnMnFeCuMgSi

Composition (%)Alloy

0.86±0.100.80±0.13-17.1±0.616.3±1.1-25.6±1.224.1±1.5-#80.76±0.120.71±0.080.92±0.0315.6±0.416.4±1.615.6±0.722.5±1.522.8±2.523.8±1.0#7

14.05±1.7813.73±2.1014.61±3.6312.6±0.912.8±1.311.7±0.927.1±1.127.4±2.225.5±0.6#3

0.96±0.141.02±0.12-22.3±0.619.8±0.2-32.8±2.331.8±1.8-#9

1.92±0.302.35±0.522.15±0.1117.0±2.715.2±1.114.8±1.130.4±2.529.8±2.229.1±1.3#62.39±0.792.78±1.242.15±0.6714.4±0.515.0±2.313.7±1.027.7±3.029.5±4.827.1±4.6#53.71±1.134.6±0.953.78±0.8614.0±1.314.4±1.213.7±1.328.6±3.130.0±2.328.8±2.9#4

-1.09±0.145.51±0.39-23.0±3.713.2±0.2-34.0±1.633.9±1.1#21.62±0.62.51±0.3416.96±0.7816.3±1.316.7±0.210.0±0.529.3±3.131.6±1.132.8±0.3#1

>30days10days1day>30days10days1day>30days10days1day

e (%)YS (0.2%, Ksi)TS (Ksi)Alloy

Mechanical Properties Measured in Tests for Defining Target Alloys

Compositions of Target andReference Alloys

Measured

00.1830.0050.0010.0280.0870.0730.4287.04Measured

-0.25-0.350.350.60.250.2-0.456.5-7.5SpecifiedA356

00.0560.0842.580.2291.013.560.059.07Measured

--0.530.51.33-40.17.5-9.5SpecifiedA380

0.0010.0080.0030.0020.390.241.992.5311.06

----0.3-0.50.15-0.251.5-2.52-310-12TargetAMC1045

0.0190.0070.0040.0010.400.212.012.4911.21Measured

0.02---0.40.32.02.511.0TargetAMC1045*

0.0210.2160.0083.060.4990.743.050.2989.70Measured

0.020.2<0.13.00.50.73.00.39.5TargetAMC380*

SrTiNiZnMnFeCuMgSiComposition (%)

Alloy

2.55±0.4614.5±0.125.7±1.0>302.51±0.2113.4±0.224.6±0.773.21±0.9611.9±0.523.8±2.11

A356

0.81±0.0323.8±1.030.9±1.1>300.98±0.1622.1±1.431.4±0.671.15±0.1618.7±0.829.6±2.81

A380

1.07±0.1221.6±0.733.0±1.1>301.11±0.1119.7±0.831.7±0.671.28±0.2317.9±1.431.1±1.51

AMC1045

1.00±0.1121.1±0.831.3±1.8>300.98±0.0520.8±0.830.9±1.071.19±0.0718.8±0.430.8±0.31

AMC1045*

1.49±0.1626.1±0.538.6±1.3>301.51±0.1925.6±1.038.2±0.771.50±0.1622.4±1.435.7±1.21

AMC380*

Elongation (%)YS (Ksi)UTS (Ksi)Tensile PropertyTest Time

(Day after Cast)Alloy

Mechanical Propertiesof Target and Reference Alloys

Typical Tensile Propertiesof Permanent Mold Test Bars

0

10

20

30

40

50

0 0.4 0.8 1.2 1.6 2

Elongation (%)

Str

en

gth

(K

si)

AMC 380*

AMC 1045*

Commercial A380

AMC380* Commercial A380

Microstructuresof Target and Reference Alloys

AMC1045* AMC1045

Microstructuresof Target and Reference Alloys

The microstructures of all the target alloys arefiner than commercial A380, especially the Fe-rich phases … not only fewer and finer but alsothe morphology being less detrimental.

Overall tensile properties of alloy AMC380* aremuch better than those of commercial A380alloy. Thirty days after casting, TS, YS, and %of AMC380*/A380 alloys are 38.6/30.9 Ksi,26.1/23.8 Ksi, and 1.49/0.81 %; increases ofabout 25%, 9.7%, and 84%, respectively.

The AMC1045* and AMC1045 alloys also showhigher TS and e% but slightly lower YS.

Results

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 A380:

0.8123.830.915-20Permanent Mold2.97±0.722.7±0.445.4±26-10Die Cast

3-423-2643-47-SpecificationElongation (%)YS (Ksi)TS (Ksi)DAS (µm)Condition

Validation of target alloys at Contech and PremierTool & Die Cast

Microstructural Difference Die Casting vs Permanent Mold Casting

Commercial A380 alloys

Die Cast Permanent Mold Cast

Acknowledgements

• AMC’s PRO-ACT program is sponsored by theDefense Supply Center Philadelphia,Philadelphia, PA, Defense Logistics Agency, Ft.Belvoir, VA.

• Contech Corp.Premier Tool & Die Cast

• ACRC Consortium Members.