A New Fluidity Die for Castability Evaluation of High

Pressure Die Cast AlloysA.D. Klarner, E. Cinkilic, Y. Lu, J. Brevick, A.A. Luo

The Ohio State UniversityJ. Shah

Product Development & Analysis (PDA) LLCM. Zolnowski

Boeing Research and TechnologyX. Yan

Alcoa Technical Center

LIFT - Melt 5B Project LIFT (Lightweight Innovations for Tomorrow) Project title: Thin-Wall Aluminum Die Casting

Development Project Topics: Alloys (Lift380 and EZCast) HPDC of test specimens and fluidity die

studies Microstructure characterization and modeling Cost modeling Industrial application: side impact beam

(CANMET)

Thin-Wall Aluminum Die Casting DevelopmentProject Team

Principal investigator: Mike Zolnowski, Boeing Industry partners:

Alcoa (Xinyan Yan)American Foundry Association (Zayna Conner, Tom Prucha)Boeing (Mike Zolnowski, Russ Cochran)Eaton (Matt Otte)North American Die Casting Association (Steve Udvardy, Beau Glim)Product Development & Analysis (Jiten Shah)

University/Research partners:Massachusetts Institute of Technology (R. Kirchain, M. Farooq)Ohio State University (A. Luo, J. Brevick, A. Klarner, E. Cinkilic)Southwest Research Institute (D. Riha)University of Michigan (J. Allison, T. Berman, Q. Shi)Worcester Polytechnic Institute (D. Apelian, L. Wang, J. Curto)

International partner: CANMET Materials (Kumar Sadayappan)

Develop super vacuum die casting with shortened heat treatment and ICME for 300 series (Al-Si-Cu-Mg based) die casting alloys

Improve strength and maintain ductility, reduce the minimum wall thickness (up to 40%) and weight (up to 20%).

Reduce quality variability and establish reliable minimum (not typical) properties of HPDC for design analysis.

Explore new design methods of lightweight castings using local mechanical properties predicted by ICME versus current casting design using minimum properties leading to overdesign and increased weight.

Deliverables will be design guidelines and property specifications for thin-wall aluminum die casting and ICME models for thin-wall casting design with location-specific properties.

Thin-Wall Aluminum Die Casting DevelopmentProject Objectives

Slide provided by Mike Zolnowski (SAE 2017)

From Micro to MacroFrom Research to Implementation;Thin-Wall Aluminum Die Casting Development

Slide provided by Mike Zolnowski (SAE 2017)

Experimental Alloys

Alloy Si Fe Cu Mg Mn Ni Zn Sr Ti AlEZCast 8.55 0.11 - 0.28 0.56 0.006 - 0.010 0.008 bal.Lift380 8.83 0.2 3.5 0.29 0.21 0.047 0.11 0.025 0.073 bal.A380.1 8.50 1.0 3.5 0.10 0.50 - 3.00 - 0.350 bal.

Alloy Liquidus (°C)

FCC Formation

(°C)

Solidus (°C)

Solidification Range (°C)

Fraction of Eutectic Liquid

EZCast 605 604 553 52 0.623Lift380 590 590 481 109 0.739A380 644 584 344 300 0.644

Higher fraction of eutectic liquid promotes better fluidity

Lift380 - lower solidus EZCast - small solidification range

Fluidity Die Studies Fluidity is a very important property in casting

especially for large thin-walled structural castings Thin-wall ⟶ fast cooling rate Very long flow distances

Currently most fluidity studies are in gravity casting condition Fluidity spiral test Vacuum fluidity test (Ragone)

Studies under HPDC conditions High pressures Fast cooling rates High velocities

2017 “International Magnesium Association Award of Excellence –Automotive Cast Product” (in collaboration with GM and Meridian)

Fluidity Die Goals Develop a die which is able to test the fluidity by

measuring experimental flow length ‘3D’ flow, to mimic real castings Thin wall sections of varying thicknesses, current

industry standard (3mm) to future (1mm) Effects of different processing parameters Effects of different alloys

Use simulation software to predict fluidity by flow lengths depending on alloy properties from CALPHAD Use experimental results to verify simulation results

Fluidity Die Design Three multi-dimensional thin-wall passages 1, 2, 3 mm wall thicknesses

(current thin wall castings to future)

Die designed by PDA (Jiten Shah) with input from Melt 5b team

Cooling Rates of Thin Walled Sections EZCast at melt temperature of

606 °C.

Average cooling rate is computed between temperatures 605 °C and 553 °C.

1 mm plate has the highest cooling rate with ~300 °C/s. 2 mm is ~200 °C/s while 3 mm is ~100 °C/s.

Rim of the plate has higher cooling rate than the middle

Unit: °C/s

𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 =𝑇𝑇𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢 − 𝑇𝑇𝑙𝑙𝑙𝑙𝑙𝑙𝑢𝑢𝑢𝑢𝑟𝑟𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢𝑢 − 𝑟𝑟𝑙𝑙𝑙𝑙𝑙𝑙𝑢𝑢𝑢𝑢

Tupper = liquidusTlower = solidus

EZCast

Simulations of Alloys at Same Temperature: High Temps

Same melt temperature (645 °C) for both cases At high temperatures, both alloys exhibit good fluidity EZCast has more uniform metal front with these parameters

74.5% filled, same simulated time

89.9% filled, same simulated time

Tliq 587.6

Tsol 505.6

Unit: °C

EZCast

Lift380

EZCast Lift380 EZCast Lift380

Simulations of Alloys at Same Temperature: Low Temps

Simulations preformed at 577°C Lift380 shows better fluidity when both alloy are at the same low

temperature - due to lower solidus temperature

Lift380Tsol 505.6

EZCast

Unit: °C

End of simulation

EZCast Lift380 EZCast Lift380

80.8% filled 85.7% filled

High Pressure Die Casting Cell at OSU Bulher 250 ton DCM Fondarex super vacuum

System (not used in these experiments)

2 furnaces allows for both magnesium and aluminum

Rimrock robotic ladling system

Rotary degassing unit (Pyrotek Star 2500)

HPDC Experimental Setup Gas furnace temperature ~100°C superheat Die temperature ~150°C, no oil lines 2 experimental aluminum alloys EZCast Lift380

Variable processing parameters Fast shot speed (0.5m/s to 5m/s; 4m/s to

40m/s gate velocity ) Melt volume (via changing ladle angle)

Flow Length Measurements

Two measurement methods ‘Good metal front’ - gate to

the point at which the metal front was disturbed

‘Full flow’ – gate to last point of flow

AlloyAverage Flow Length (full flow) Average

Superheat (°C)

Average Die Temperature

(°C)1mm 2mm 3mm

EZCast 38.2 71.7 199.5 93.9 141.5Lift380 52.1 110.8 187.3 95.4 132.3

0

65115

200

Flow Length Results

Full Flow

3mm Full Castings Total % FullEZCast 23 24 96%Lift380 16 21 76%

Flow Length Results

3mm would fill and backfill into thinner sections

1 and 2mm sections showed incomplete filling

EZCast Lift380

AlloyAverage Flow Length

(good metal front)1mm 2mm 3mm

EZCast 8.1 24.3 196.1

Lift380 11.9 79.4 184.9

Flow Length vs Shot Speed

Found linear response with shot speed 3mm filled all times above 1.5 m/s

2mm thin-wall had around double the flow length compared to 1mm Half average cooling rate

Full Flow

Good Metal Front

Speed (m/s) 1mm 2mm 3mm0.5 3.5 41.8 184.71.0 2.7 63.8 177.71.5 17.3 86.1 200.02.0 29.3 74.5 200.03.0 59.7 108.1 200.04.0 75.3 175.8 200.05.0 75.0 165.3 200.0

Wall Thinkness

0.5m/s

1m/s 1.5m/s

2m/s

3m/s 4m/s 5m/s

Alloy: Lift380

Flow Length vs Shot Speed

Simulations vs Partial Shots(Controlling Shot Volume)

As shot volume increases, flow length increases

Used reduced metal pours to create partial shots to look at metal front and compare to simulations

Alloy: Lift380

Simulations vs Actual Castings

Sample EZCast #92 had low furnace temperature (642°C)

Caused early solidification and fill pattern matches that of simulation at partial fill (80%)

EZCast at 80.8% filled

Simulations vs Actual Castings

Backfilling of 1mm section is shown in simulations Happened in experiments when temperature was low Quick solidification in 1mm

EZCast

EZCast fraction solid at final filling

Industry Application: Side Impact Beam

29’’

2.85’’

Length ~29 inches, Width ~2.85 inchesThickness 3mm through most of partPart Volume = 225cm^3 (~600g)

Industry Casting Trial at CANMETSide Impact Beam

Casting Trials conducted at CANMET, April 2017

Process parameters (velocity, melt temp, fill time) found using simulation

X-ray inspection by Boeing Simulations ran with trial

process parameters and correlated with experimental porosity measurements

Industry Casting Trial at CANMETSide Impact Beam

Simulation using actual casting trial processing parameters Predicted more porosity in Lift380 compared to EZCast

EZCast Lift380

Predicted primary shrinkage

Slide and simulation provided by PDA (Jiten Shah)

Side Impact Beam: Casting Quality

Typical E15-30

Worst E2

Sample E15 simulated, no indications

Lower plunger velocity, poor vacuum

EZCast

Slide and simulation provided by PDA (Jiten Shah)

Radiography performed by a Boeing certified level 3

technician

Side Impact Beam: Casting Quality

Typical samples: never were consistently defect free, matches simulation

No vacuum applied (1010mbar), higher melt temperature (757°C)

Lift380

Typical

Worst: L2

Slide and simulation provided by PDA (Jiten Shah)

Radiography performed by a Boeing certified level 3

technician

Conclusions The new “fluidity die” can be used to evaluate

castability and optimize processing parameters for different alloys by measuring flow length at different thicknesses.

Flow simulations using alloy specific properties (viscosity, etc.) can predict the flow length and pattern with reasonable accuracy.

Two experimental alloys, EZCast and LIFT, showed varied castability at different melt temperatures. Both alloys performed well in the “fluidity die” casting trials (at OSU), and industrial “side impact beam” casting trials (at CANMET).

Acknowledgements LIFT (Lightweight Innovations for Tomorrow) Entire LIFT Melt5b Project Team Bill Tullos, lead casting engineer at OSU OSU Center for Design and Manufacturing Excellence

(CDME) and Simulation Innovation and Modeling Center (SIMCenter)