SSM PROCESSING R&D:

PROGRESS REPORTD. Apelian and M. Makhlouf

www.wpi.edu/+mpiNADCA R&D Committee Meeting

October 16, 2002

ACRC Consortium Members

September 2002

• Alcan International Ltd.

• Aluminum Company of America

• Aluminum Pechiney

• Amcast Industrial Corp.

• BMW AG

• Briggs & Stratton Corp.

• Buhler Inc.

• Chem-Trend Inc.

• Citation Corp.

• Consolidated Metco

• Daimler Chrysler Corp.

• Elkem Aluminum ANS

• Ford Motor Co.

• J. L. French International Ltd.

• General Aluminum Manufacturing Co.

• General Motors Corp.

• Harley-Davidson Motor Co.

• Hayes Lemmerz International, Inc.

• Heraeus Electro-Nite Co.

• Hitchcock Industries, Inc.

• Hydro Aluminum A.S.(VAW- Hydro Germany)

• IdraPrince Corp.

• Intermet Corp.

• Kennedy Die Castings, Inc.

• Leggett & Platt Aluminum Group

• Madison-Kipp Corp.

• Mercury Marine

• Metallurg Aluminum

• Montupet

• NEMAK

• North American Die Casting (NADCA)

• Ormet/Formcast, Inc.

• Palmer Foundry, Inc.

• Phillips Plastics

• Salzburger Aluminum AG

• Selee Corp.

• SPX Corp.

• Superior Industries International, Inc.

• Teksid Aluminum S.p.A.

• THT Presses

• TRW Automotive

• Visteon Chassis Systems

Semi-Solid Processing Studies

Projects Completed (1998 – 2001)

1. Yield Stress Measurements and Quantitative Microstructure Characterization (WPI)

2. Modeling of Rheology in Semi-Solid Alloys (WPI)

3. Optimization of Heat Treatment Conditions for Semi-Solid 357 Alloy (WPI)

4. Time Dependent Rheology of Semi-Solid Alloys (MIT)

5. Microstructural Evolution in Semi-Solid Alloys (MIT)

6. Development of Alternate Semi-Solid Aluminum Alloys (ORNL)

Semi-Solid Processing Studies

Current SSM Projects Beginning January 2002

1. A Continuous Rheoconversion Process for Production of Semi-solid Slurries (WPI)

2. High-Temperature Rheological Measurements

3. AlB2 Grain Refined Billet Route - SiBloy™ (WPI)

4. Modeling and Prediction of SSM Rheology (WPI)

Yield Stress Measurements and Quantitative Microstructure Characterization

Q. Y. Pan and D. Apelian

DOE-Funded SSM Processing Projects

• Establish yield stress vs temperature relationship for commercial semi-solid Al alloys

• Understand how processing method affects slurry yielding behavior

• Quantitatively characterize microstructural evolution of various semi-solid billets during commercial forming conditions

• Investigate the effects of semi-solid structure on the rheological behavior of commercial semi-solid billets

Yield Stress vs. Temperature (A356)

SiBloy®

GR A356

UBE A356 MHD A356

570 575 580 585 590 595 T e m p e r a t u r e ( C )

0.1

1

10

100

1000

10000

Y i e l d S t r e s s ( k P a )

SiBloy®

GR A356

UBE A356 MHD A356

Yie

ld S

tres

s (k

Pa)

SiBloy®

GR A356

UBE A356 MHD A356

570 575 580 585 590 595 T e m p e r a t u r e ( C )

0.1

1

10

100

1000

10000

Y i e l d S t r e s s ( k P a )

SiBloy®

GR A356

UBE A356 MHD A356

Yie

ld S

tres

s (k

Pa)

540 550 560 570 580 590 600Temperature (C)

0.01

0.10

1.00

10.00

100.00

1000.00

10000.00Yi

eld

Str

ess

(kP

a)

1.45×10-3

1.45×10-2

1.45×103

1.45×102

1.45×101

1.45×100

1.45×10-1

Yield S

tress(psi)MHD 357

GR 357

Yield Stress vs. Temperature (357)

MHD A356 GR A356 SiBloy

MIT A356 SIMA A357 UBE (A356)

Semi-solid Microstructure at 580°C

Image Analysis ResultsEntrapped Liquid Content (Vf) vs. Temperature

575 580 585 590 595

Temperature (C)

0

10

20

30

40

Ent

rapp

ed L

iqui

d (%

)

0

10

20

30

40575 580 585 590 595

GR A356

SiBloy

SIMA A357

MHD A356 • Vf (GR)>> Vf(MHD)

• Vf(GR): 15-30%; Vf(SIMA): 11-14%Vf(MHD): 8-10%

• ↑T⇒ Vf↓

• Little entrapped liquid in MIT and UBE billets

Time (min.)

Liquidus

Solidus

Tem

pera

ture

(°C

)

Quench

Particle Size (Dp) vs. Temperature

• ↑T⇒ Dp ↑

• SIMA: 50-80 µm

• GR: 125-185µm

• No effect on SiBloy

575 580 585 590 595

Temperature (C)

40

80

120

160

200

Par

ticle

Siz

e (u

m)

40

80

120

160

200

575 580 585 590 595

GR A356SiBloy

MHD A356 UBE

SIMA A357MIT A356

Ave

rage

Par

ticle

Siz

e (µ

m)

Image Analysis Results

Shape Factor (SF) vs. Temperature

• ↑T⇒ SF↓

• SF=1⇒Spherical

• SIMA: 1.18-1.25

• SiBloy: 1.66-1.86

575 580 585 590 595

Temperature (C)

1

1.2

1.4

1.6

1.8

2

Sha

pe F

acto

r

1

1.2

1.4

1.6

1.8

2

GR A356

SiBloy

UBE

MIT A356

SIMA A357

MHD A356

Sha

pe F

acto

r (S

F)

Image Analysis Results

Modeling of SSM ProcessesAndreas Alexandrou

Objectives:

Research Portfolio: DOE-Funded SSM Processing Projects

•Perform numerical simulations of SSM mold filling operations anddevelop codes to predict and control mold filling instabilities

•Verify rheological models using experimental simulations

Flows in 2-D Expansions: Flow patterns and casting methods

0

20

40

60

80

100

120

140

160

180

200

0.01 0.1 1 10 100 1000 10000

bubble

mound

shell

disk

transition

τ 0 = 70000Pa

Bi

ReSQUEEZE CASTING

SEMISOLID CASTING

DIE CASTING

PistonPiston SemiSemi--solid solid aluminumaluminum Cavity

Mold

SSM Modeling: Flow Instabilities

Semisolid Aluminum Slurry: Flow Instabilities

Toothpaste Instability:experimental

Toothpaste Instability:FEM simulation results for(Re=1, Bi=3, L=10)

(Courtesy of Aluminum Pechiney)

(Courtesy of Aluminum Pechiney)

Time-Dependent Rheology of Semi-Solid Alloys (MIT)

A. Kato, A. M. de Figueredo, J. Yurko and M. C. Flemings

Research Portfolio: DOE-Funded SSM Processing Projects

Accomplishments

•Obtained fundamental rheological data on microstructural evolution of semi-solid Al alloys

•Determined effects of semi-solid slurry structure on flow at shear rates typical of forming processes

•Carried out experimental simulations of SSM flow

Research Portfolio: DOE-Funded SSM Processing Projects

Shear rate (1/s)

(parallel plate, compression)

(parallel plate, rotation)

• Agreement between experiments shows that complete break down of the slurry structure occurs in milliseconds

• Results show fully broken structures at shear rates below 1000 s-1

SSM Transient Behavior (Hysteresis) in Rotational and Compression Experiments

Research Portfolio: DOE-Funded SSM Processing Projects

• Rapid shear deformation of SSM slurries leads to large decreases in viscosity

• Viscosity recovery times are longer than typical mold cavity filling times

• Once the SSM structure is fully broken, the resulting slurry becomes very fluid and remains so for relatively long times

SSM Rheology: Transient Behavior in Rotational Experiments

Microstructural Evolution in Semi-Solid Alloys (MIT)

R. Martinez, A. M. de Figueredo, J. Yurko and M. C. Flemings

Research Portfolio: DOE-Funded SSM Processing Projects

Accomplishments

Developed a new method of forming semi-solid metal structures for slurry ready applications

Research Portfolio: DOE-Funded SSM Processing Projects

MIT New SSM Approach

Research Portfolio: DOE-Funded SSM Processing Projects

Typical semi-solid structures obtained in A357 alloys by coupling forced convection with rapid heat extraction just below the liquidus temperature.Primary aluminum particles do not contain entrapped eutectic.

Processed Alloy, As cast Re-heated to 585°C and quenched

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

A Continuous Rheoconversion Process (CRP) for Production of Semi-solid Slurries

M. Findon, A. M. de Figueredo, D. Apelian, and M. Makhlouf

Objective

Develop novel, economic methods of continuously forming semisolid metal slurries for rheocasting

and thixocasting applications

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

CRP - Continuous Rheoconversion Process

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

CRP - Continuous Rheoconversion Process

– Continuous conversion of liquid to slurry– Flexible

• Thixocasting or slurry-ready• Not alloy specific• Allows for rapid adjustment of solid content• Recycling of scrap easy to incorporate

– Can be used with one melt as well – design flexibility– Reasonable operating temperature range for slurry-

ready processing– Commercially viable – patent application submitted and

in process

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

CRP MICROSTRUCTURES: A356 ALLOYS

As-cast, TL=625°C Reheated to 585°C for 10min

and quenchedin water

As-cast, TL=660°C

High Temperature Rheological MeasurementsA. M. de Figueredo, Q. Y. Pan, and D. Apelian (WPI)

N. Tonmukayakul and Q. Dzuy Nguyen (University of Adelaide)

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

Objectives

• Investigate the flow behavior of semi-solid metals under transient flow conditions

• Determine shear stress-shear rate curves during rapid shear rate transients

• Correlate the viscosity of semi-solid metals with respective structures

• Develop instrumentation and techniques for rheological characterization of SSM slurries in the casting plant

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

Shear StressResponse

ViscosityResponse

Shear Rate Sweep

0.1

1

10

100

0 0.2 0.4 0.6 0.8 1

Time (s)

Viscosity-Up

Viscosity-Down

Shear Rate

590oC fs =0.39

39 vol%

0.1

1

10

100

0 300 600 900 1200

Shear Rate (1/s)

up

down

590oC fs =0.39

39 vol%

0

500

1000

1500

2000

0 300 600 900 1200

Shear Rate (1/s)

up

down

590oC fs =0.39

39 vol%

Response of SSM 357 Alloy to Rapid Shear

Deformation

Research Portfolio: DOE-Funded SSM Processing ProjectsStarted January, 2002

• A comprehensive program for the rheological characterization of SSM slurries has been established at MPI.

•This program is employing state of the art rheometry to characterize the flow behavior of SSM slurries under conditions of rapid deformation

Research Portfolio: DOE-Funded SSM Processing ProjectsStarting January, 2002

AlB2 Grain Refined SSM Billet Route

Objectives

Investigate microstructural refinement in casting aluminum alloys by addition of Si-B master alloy (SiBloy® technology), and develop economic processes for the production of high-quality SSM feedstock

580°C 582°C 585°C 590°C

580°C 582°C 585°C 590°C

SiBloy @ Billet Center

GR A356 @ Billet Center

Semi-solid Microstructures of SiBloy and GR A356 billets

Quantitative Data

576 580 584 588 592

Temperature (C)

0

4

8

12

Ent

rapp

ed L

iqui

d (%

)

0

4

8

12

A356

SiBloy

Time (min.)

Liquidus

Solidus

Tem

pera

ture

(°C

)

Quench

576 580 584 588 592

Temperature (C)

0

4

8

12

16

Ent

rapp

ed L

iqui

d (%

)

0

4

8

12

16

A356SiBloy

Billet Center Billet Edge

Quantitative Data

576 580 584 588 592

Temperature (C)

80

120

160

200

Par

ticle

Siz

e (u

m)

80

120

160

200A356

SiBloy

576 580 584 588 592

Temperature (C)

80

120

160

Par

ticle

Siz

e (u

m)

80

120

160A356

SiBloy

Billet Center Billet Edge

576 580 584 588 592

Temperature (C)

0.8

1.2

1.6

2

Sha

pe F

acto

r

0.8

1.2

1.6

2

A356

SiBloy

576 580 584 588 592

Temperature (C)

0.8

1.2

1.6

2

Sha

pe F

acto

r

0.8

1.2

1.6

2

A356

SiBloy

Quantitative Data

Billet Center Billet Edge

YS Measurement Results

570 575 580 585 590 595

Temperature (C)

0.1

1

10

100

1000

10000Y

ield

Str

ess

(kP

a)

0.1

1

10

100

1000

10000

GR A356

Unmodified SiBloy

Modified SiBloy

Yield stress vs. temperature

Research Portfolio: DOE-Funded SSM Processing ProjectsStarting January, 2002

Modeling and Prediction of SSM Rheology

A. Alexandrou and Q.Y.Pan

Objectives

Develop simulation tools to understand and control SSM flow instabilities in mold filing operations

Constant Shear RateTemp.: 585°CHeating rate: 49°C/min.Shear Rate: 5x10-3s-1; 8.33x10-3s-1

Constant Shear Force

MethodologyV

Temp.: 585°CHeating rate: 49°C/min.Shear Force: 2N; 4N

F

Time (min.)

Liquidus

Solidus

Tem

pera

ture

(°C

)

585°C

Apparatus

∆T: ≤ 1°C

LR: 0.001N

Flow Behavior of SSM A356 at Different Shear Strains

Experiment Simulation

(T: 585°C; shear rate: 5.0×10-3s-1; Shear Strains: 0, 19.5, and 31.9)

1 .0 1

1.01

1

1

1.01

0.99

0.99

R0 0.25 0.5 0.75 1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

ZStagnantZone

Stagnant zone

Stagnant zone

Fluid Flow

Fluid Flow

Fluid Flow Fluid Flow

1. 01

1 .0 1

0 .99

0.99

1

1

R0 0.25 0.5 0.75 1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

ZS tag nantZone

S tagnant zo ne

S tag nant zone

Fluid Flow

Fluid Flow

Fluid Flow

Stress Distribution under Compression

(Bi=5, Re=1, F=-1.)

Early Stage Late Stage

SSM processing of Hyper-eutectic Al-Si alloys

Deepak Saha, Babu Dasgupta* and D.Apelian* SPX Contech, MI, USA

Objectives

Processing of 390 alloy via the Rheo-casting (Slurry-on-Demand) route having a consistent and uniform distribution of primary Si

Research Portfolio: Industrial Internship Funded SSM Processing Projects

Conceptual Framework: Diffusion Solidification

12.6

% Si à

L1@ 760 0CAl-25% Si Alloy

L2+S@ 550 0CSibloyR (Fraction solid ~ 85 %)

Research Portfolio: Industrial Internship Funded SSM Processing Projects

Conceptual Framework

Control of uniformly distributed Si Phase is attained by heat balance

•Heat released

(Cooling from Liquid temperature to Liquidus + Latent Heat from the nucleating

and growing primary Si phase)

• Heat removal

(The mixing of the Eutectic liquid + Dissolution of Primary Al)

Heat Released = Heat Absorbed

Research Portfolio: Industrial Internship Funded SSM Processing Projects

Example: SibloyR at 550 0C mixed with 25% Al-Si at 760 0C (Final Temperature 590 0C)

Research Portfolio: Industrial Internship Funded SSM Processing Projects