This document provides an overview of semi-solid metal forming research conducted by the CSIR in South Africa. It discusses the background of semi-solid metal forming including thixoforming and rheocasting. It describes the CSIR's approach to research, which involves developing the total product solution. Key research areas covered include processing cast and wrought aluminum alloys in semi-solid form, heat treatment, and product development. Infrastructure for research includes high pressure die casting and semi-solid billet production equipment. Research demonstrates microstructure and properties of semi-solid formed alloys can meet or exceed specifications.

1. Semi-Solid Metal Forming
Pierre Rossouw
02 December 2010
© CSIR 2010
www.csir.co.za

2. Outline
• Background
-
Organogram of MSM
Research Focus (ACT)
• SSM Forming
-
Background
-
CSIR’S Approach
Current Research
•
•
•
© CSIR 2010
Casting Alloys
Product Development
Wrought Alloys
Future
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3. Background
MMP Organogram
Metals & Metals Processes
Dr Willie du Preez
CA Assistance
Christelle Stearn
Mary Mojalefa
Rebecca Myelase(contr)
Primary Processes
Powder Metallurgy
Technologies
Dr Hilda Chikwanda
Neels Babst, Duncan Hope
Ronel Laage
Shaan Oosthuizen
Ghislain Tshilombo
Eugene Swanepoel
Jaco Swanepoel
Dewald Terblanche
Danie Snyman
Advanced Casting
Technologies
Dr Sagren Govender
Jeff Benson
Dr Chris Machio
Dr Lethu Chikosha
Maje Phasha
Sylvester Bolokang
Tafadzwa Mushove
Given Lesejane
Lerato Raganya (intern)
Dawie van Vuuren
Project Management
Quality Facilitation
Christelle Stearn
Pierre Rossouw
Hein Möller
Ulyate Curle
Kalenda Mutombo
Sigqibo Camagu
Nonjabuliso Mazibuko
Peter Malesa
Sam Papo
Dr Lillian Ivanchev(IC)
William Tefu (contr)
Visiting Researchers
CSIR-Cermalab
CSIR-Cermalab
Bruce Berger (Ops. Man.)
Bruce Berger (Ops. Man.)
Suzan Nchabeleng (100%)
Danie Snyman (20%)
Dr Wim Richter (20%)
Chris McDuling
Erich Güldenpfennig
Levy Chauke
MMP Laboratory
Mechanical Testing, Metallurgical & High Temperature Materials Testing
© CSIR 2010
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Engineering Design &
Analysis
Vacant
Gary Corderley
Lesley Harris
Markus Coetzer
Filipe Pereira
Danie Wilkins
Martin Williams
Marius Grobler
David Ntuli (contr)

4. Background
Overview of Casting Research
Advanced Casting
HPDC
SSM
•New tool materials
•Improving net yield
•Foundry practice
for Al
•Development of a
VIVC HPDC Machine
•Squeeze casting
•Near Net shape
forming of AlMMCs
•SSM processing of
aluminium alloys
•Heat treatment of
SSM castings
•Development of the
CSIR-RCS
•Near Net shape
forming of AlMMCs
Funded by CSIR Parliamentary Grant
Funded by CSIR Parliamentary Grant and LMDN
Funded by DST
Funded by LMDN
© CSIR 2010
www.csir.co.za
Investment
Casting
•Titanium(90%)
•Counter gravity
casting of Aluminium
Magnesium
alloys(5%)
•Near net shape
forming of
AlMMCs(5%)

5. Semi-Solid Metal Forming
Background
1. THIXOFORMING
2. RHEOCASTING
© CSIR 2010
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6. Semi-Solid Metal Forming
Background - Potential Benefits
•
High wall thicknesses and different wall thicknesses can be
designed
•
•
Low gas porosity due to laminar filling and good airing
•
•
Production of thin walled components
•
•
•
•
Joining by LASER, MIG or WIG welding possible
Low solidification porosity due to a high solid fraction proportion
(fsolid ~50%)
Allows for the casting of wide range of alloys inclusive of high
strength wrought alloys.
Heat treatment from T0 - T7 possible
Near netshape or netshape parts production
Improved tool life
© CSIR 2010
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7. Semi-Solid Metal Forming
Background – Thixo VS Rheocasting
LIQUID
THIXO
RHEO
•CASTING
Known since 3000 BC
Liquidus temperature
Globular structure
formation
•SEMI-SOLID METAL
CASTING/FORMING
SEMI-SOLID
Known since 1973 AD
Solidus temperature
•HOT FORMING
Known since 3500 BC
SOLID
•COLD FORMING
Known since 4000 BC
Ambient temperature
© CSIR 2010
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8. Semi-Solid Metal Forming
Background- Thixoforming
SSM FEEDSTOCK
SSM FORMING PROCESS
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9. Semi-Solid Metal Forming
Background- Thixoforming
Disadvantages
• High cost of feedstock material compared to normal foundry
alloys
• In order to meet production rates multiple induction heating
stations are required which requires high capital expenditure
• The scrap produced cannot be recycled on site and is also
devalued significantly
• The feedstock is supplied in specific lengths, which means
there would be additional scrap created by off cuts.
• During reheating oxidation of the billet surface occurs
therefore dies have to be designed to remove oxides during
the forming process.
• During reheating there are liquid metal losses from the billet
prior to casting.
© CSIR 2010
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10. Semi-Solid Metal Forming
Background- Rheocasting
Transfer
Cool
Liquid Metal
Semi-solid metal with
round grain structure
High Pressure Die Casting
© CSIR 2010
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11. Semi-Solid Metal Forming
Background- Rheocasting
Advantages
Cost of material same as standard
casting alloys
Disadvantages
Hydrogen Absorption
Process consistency
Semi-solid state achieved direct
from liquid.
Oxidation reduced – reduced oxide
entrapment.
Reduced loss of metal during
reheating.
SSM scrap can be recycled in
house.
© CSIR 2010
www.csir.co.za

12. Semi-Solid Metal Forming
Background- SSM Forming Research in SA
• 2000 – 2002 Rheo-casting process Developed and
•
•
patented
2003 – 2005 Development of industrial prototype –
CSIR funded
2006 – 2010
-
Development of the CSIR-RCS
SSM forming of Al alloys
Heat treatment
Development of component for SSM forming
Established Research Infrastructure
Commercialisation of CSIR-RCS
© CSIR 2010
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13. SSM Research at the CSIR
Goal
To provide the total SSM product
solution to the prospective client
© CSIR 2010
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14. SSM Research at the CSIR
Approach
• Process Development
•RCS
•HPDC
•Material
•Alloy
•Heat treatment
•Material property
•Product
•Customer specification
•Product design
•Die design
•Product qualification
•Lifeing
© CSIR 2010
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15. SSM Research at the CSIR
Research Areas
Overview of SSM research
• Development of the CSIR-RCS for
commercialisation
• SSM processing of cast and wrought
aluminium alloys
• Heat treatment
• Corrosion
• Mechanical properties
• Product development
© CSIR 2010
www.csir.co.za

16. SSM Research at the CSIR
Infrastructure
130 Ton Shot Controlled HPDC
Machine
© CSIR 2010
CSIR – RCS Lab Prototype
www.csir.co.za

17. SSM Research at the CSIR
Infrastructure
© CSIR 2010
www.csir.co.za

18. SSM Research at the CSIR
Infrastructure
Dosing Furnace
Industrial scale prototype of
CSIR SSM billet machine
630 Ton LK shot control die casting machine
© CSIR 2010
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19. SSM Research at the CSIR
Alloys Processed
Other
Cast
Wrought
Pure Al
A356
2024
Al-12Si
F357
6082
A206
6004
A201
6005
7075
7150
7278
© CSIR 2010
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MMC
SiCp/Al

20. SSM Processing of Casting
Alloys
© CSIR 2010
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21. SSM Research at the CSIR
Microstructure of SSM formed A356 & F357
A356, F; Etched
F357; F; Etched
A356, T6; Etched
F357, T6; Etched
© CSIR 2010
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22. SSM Research at the CSIR
Tensile properties obtained for Casting Alloys
Alloy
YS /MPa
UTS /MPa
Elongation /%
A201-T6
297
407
13.4
261
317
6.7
312
355
6.0
(Low Mn)
A356-T6
(0.35% Mg)
F357-T6
(0.62% Mg)
Note: The properties presented are very dependent on composition and heat treatment process applied.
© CSIR 2010
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23. SSM Research at the CSIR
Influence of Mg on Tensile properties of A356/F357 Alloys
© CSIR 2010
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24. SSM Research at the CSIR
Heat Treatment of Cast and Wrought Alloys
130
120
110
VHN
100
90
80
70
6082: 0NA
6082: 120NA
6004: 0NA
6004: 120NA
A356: 0NA
A356: 120NA
60
50
40
30
0
1
10
t at 180oC (h)
© CSIR 2010
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100

25. SSM Processing of Wrought
Alloys
© CSIR 2010
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26. SSM Research at the CSIR
Microstructure of SSM formed GR 7075
7075 with no TiB2; F; Etched
7075 with medium TiB2; F; Etched
7075 with high TiB2; F; Etched
© CSIR 2010
www.csir.co.za

27. SSM Research at the CSIR
Microstructure of SSM formed GR 7075
no TiB2; T6; Etched
7075 with medium TiB2; T6; Etched
7075 with high TiB2; T6; Etched
© CSIR 2010
www.csir.co.za

28. SSM Research at the CSIR
Tensile properties obtained for GR 7075
• Tensile test results; T6
YS /MPa
UTS /MPa
Elongation /%
no TiB2
467
513
3.2
medium TiB2
458
516
4.5
high TiB2
453
516
5.3
455
531
7.0
Alloy
Minimum
specification
© CSIR 2010
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29. SSM Research at the CSIR
Tensile properties obtained for GR 7075
• Tensile results relative to minimum specification; T6
Alloy
YS /%
UTS /%
Elongation /%
no TiB2
103
97
46
medium TiB2
101
97
64
high TiB2
100
97
76
© CSIR 2010
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30. SSM Research at the CSIR
Microstructure of SSM Processed Wrought Alloys
• Microstructure: 2024
T6
F
(Etched)
© CSIR 2010
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31. SSM Research at the CSIR
Microstructure of SSM Processed Wrought Alloys
• Microstructure: 6082
T6
F
(Etched)
© CSIR 2010
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32. SSM Research at the CSIR
Microstructure of SSM Processed Wrought Alloys
• Microstructure: 7075
T6
F
(Etched)
© CSIR 2009
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33. SSM Research at the CSIR
Tensile properties obtained for Wrought Alloys
Alloy
YS /MPa
UTS /MPa
Elongation /%
2024-T6
351
385
5.1
Spec. min.
345
427
5.0
6082-T6
341
365
3.6
Spec. min.
260
310
10.0
7075-T6
467
513
3.2
Spec. min.
455
531
7.0
© CSIR 2010
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34. SSM Research at the CSIR
Tensile properties obtained for Wrought Alloys
Tensile results relative to minimum specification
Alloy
YS /%
UTS /%
Elongation /%
2024-T6
102
90
102
6082-T6
131
118
36
7075-T6
103
97
46
© CSIR 2010
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35. © CSIR 2010
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36. SSM Research at the CSIR
Microstructure of SSM Processed High Purity Al
SSM HPDC High Purity Aluminium
© CSIR 2010
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37. SSM Research at the CSIR
Microstructure of SSM Processed Al-Si Eutectic Alloy
Conventional Eutectic
(No SSM Processing)
© CSIR 2010
Eutectic
Rheo-processed and HPDC
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38. © CSIR 2010
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39. SSM Research at the CSIR
SSM HPDC of a Brake Calliper
•
SSM Castings
-
-
Produced using the Industrial Scale HPDC Cell
• CSIR-RCS
• Dosing Furnace
• LK 630 ton shot controlled HPDC machine
Alloy - A356
• Main Objective:
-
Demonstrate process consistency
© CSIR 2010
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40. SSM Research at the CSIR
SSM HPDC of a Brake Calliper
© CSIR 2010
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41. SSM Research at the CSIR
SSM HPDC of a Brake Calliper
Surface Liquid Segregation
© CSIR 2010
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42. SSM Research at the CSIR
SSM HPDC of a Brake Calliper
Hardness profiles through a cross section of SSM-HPDC brake calipers
F
T4 (540-1)
T4 (540-6)
T5 (180-4)
T5 (170-6)
T6(540-1,20NA,180-4)
T6(540-6,20NA,170-6)
150
VHN
130
110
90
70
50
0
2
4
6
8
10
12
Depth (mm)
© CSIR 2009
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14
16
18
20

43. SSM Research at the CSIR
Product Development Case Study – Engine Mounting Bracket
Original component
Component redesigned
for SSM forming
© CSIR 2010
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44. © CSIR 2010
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45. SSM Research at the CSIR
Product Development Case Study – Engine Mounting Bracket
X-ray Analysis of a Casting
© CSIR 2010
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46. SSM Research at the CSIR
Product Development Case Study – Engine Mounting Bracket
Mechanical Properties
Tensile samples were
machined from this section
Summary of Mechanical Properties from Selected Castings
YS,
UTS,
A,
Condition
HB
MPa
MPa
%
F
71.2
104.3
180.0
5.2
T4
84.0
144.3
255.4
13.3
T6
109.7
255.5
315.2
5.38
T5
91.6
194.0
262.3
4.7
Minimum
85
167
275
1.5
requirements
© CSIR 2010
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47. SSM Research at the CSIR
Product Development – New Opportunities
•
Partner interest after initial discussions:
-
•
Component is identified
Al-alloy of wrought composition
Must meet minimum requirements of the customer
- Mechanical properties
- Cost
Partner to specify other applicable material properties
Intent:
-
Willing to apply CSIR-RCS technology if successful
Create manufacturing facility with jobs in South Africa
(Localisation)
© CSIR 2010
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48. CSIR-RCS: Large scale (2)
SSM Research at the CSIR
Product Development – New Opportunities
Preliminary Work
•
Component: Engine mounting bracket
-
•
Commercial 7075 (~ 150 kg furnace); A356
Rheo-processing parameters (pouring & SSM temp.)
HPDC shot parameters (velocity profile & intensification)
X-ray evaluation (defects)
Heat treatments (apply knowl. from plates)
Mechanical properties (compare with knowl. from plates)
Aim:
Preparation of niche component production
© CSIR 2010
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49. © CSIR 2010
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50. SSM Research at the CSIR
Future Work
•
•
•
•
•
Product development for client
SSM forming of high strength wrought alloys
Optimisation of heat treatments
Alloy development
Develop data base of mechanical properties
-
Tensile
Fatigue
Fracture
• Evaluation surface properties
-
Corrosion
Coatings
© CSIR 2010
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51. sgovender@csir.co.za
ucurle@csir.co.za
prossouw@csir.co.za
© CSIR 2010
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