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CANMET- MTL May 11, 2011 Hamilton, Ontario, Canada Grain Refinement of Magnesium Alloys Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe by CONFORM: A Continuous Severe Plastic Deformation Route? Plastic Deformation Route? Youliang He Jian Li Robert Eagleson CANMET-MTL, Natural Resources Canada Youliang He , Jian Li, Robert Eagleson, Pei Liu, Ruby Zhang Fei Gao, Baoyun Song, Rong Fu, Guiming Wu Dalian Jiaotong University P R China Dalian Jiaotong University , P . R. China Lan Jiang McGill University

Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

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Page 1: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

May 11, 2011Hamilton, Ontario, Canada

Grain Refinement of Magnesium Alloys Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe by CONFORM: A Continuous Severe

Plastic Deformation Route?Plastic Deformation Route?

Youliang He Jian Li Robert Eagleson

CANMET-MTL, Natural Resources Canada

Youliang He, Jian Li, Robert Eagleson, Pei Liu, Ruby Zhang

Fei Gao, Baoyun Song, Rong Fu, Guiming WuDalian Jiaotong University P R ChinaDalian Jiaotong University, P. R. China

Lan JiangMcGill University

Page 2: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

What is Severe Plastic Deformation? Why SPD?

• Large Deformation Strain: > 3• No Dimension Change After Deformation • Normally a Repeatable Process• Normally a Repeatable Process• No Fracture or Damage to the Workpiece• Batch & Continuous Modes

Fabricate Ultrafine or Nano-Structured Bulk Metallic Materials.

Achieve Favourable Properties: High Strength at Room Temperature and/or Superplasticity at Moderate Temperatures and High Strain Rates.

Commercial Products: Sputtering Targets, Dental Implants, Fasteners, …

Materials Processed: Al, Mg, Cu, Ti, Steel, …

Significantly Refined & Uniform Microstructure/Nanostructure

Page 3: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Severe Plastic Deformation: Batch Operation Mode

ECAP HPT CEC TE

• Equal Channel Angular Pressing

• High Pressure Torsion

Good Grain Refining Effect Ultrafine or Nano Grains

Possible• Cyclic Extrusion

Compression• Twist Extrusion

M lti Di ti l F i

Batch Operation ModeSmall Work PieceLow Useful Material Rate

• Multi-Directional Forging• etc. R. Z. Valiev et al., JOM, 2006

Page 4: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Severe Plastic Deformation: Continuous Operation Mode

• Repetitive Corrugation & Continuous Operation:

RCS ARB

p gStraightening

• Accumulative Roll Bonding

pHigher Efficiency

Large-Size Sheets PossibleCracks (Edge or Surface)

• Continuous Confined Strip Shearing

• etc.

Inhomogeneous Thickness Reduction Surface Treatment

R. Z. Valiev et al., JOM, 2006

Page 5: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Severe Plastic Deformation: ECAP + Continuous Feeding

RollerZhang et al 2006

Shoe

Feed stock

RollerZhang et al., 2006

Wheel

AbutmentAbutment

ECAP with Continuous

Feeding

ECAP C f

• Large Shear Strain

ECAP-Conform

Zhu et al., 2006

CONFORM

Large Shear Strain• Hydrostatic Pressure

Srinivasan et al., 2006

Page 6: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Continuous Extrusion Forming: A Combined Deformation Process

Roller Wheel Shoe

AsymmetricRolling Cu

Shear

ECAP Al

Abutment

Extrusion

Friction force as driving Invented in UK Maximum Extrusion

Materials:

Friction force as driving force: low energy consumption

High production rate Continuous production

Invented in UKAtomic Energy Authority in 1970’s

Maximum Extrusion Width: Al ~130 mm, Cu ~320 mm Maximum Product Area: Al ~13000 mm2Materials:

Al, Cu, Pb, Zn, Mg Continuous production Low scrap levels

Al ~13000 mmCu ~6400 mm2

Page 7: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

CONFORM: A Continuous Severe Plastic Deformation Route?

T. Erlien et al, NANOSPD3, 2005

Higher Effective Strain than ECAP C ti O ti

CONFORM ECAP

Continuous Operation Already Commercialized Various Product Shapes

Not Widely Recognized YetMore Research NeededMore Research Needed

Page 8: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL Application to Magnesium Alloys (AZ31)

8 mm

Extruded Cast

Feedstock Cast Microstructure

Both cast and extruded rods can be used as feedstock

CONFORM Machine

Both cast and extruded rods can be used as feedstockHeating of the feedstock and the die chamber neededOne pass CONFORM extrusion onlyNo heat treatment after CONFORM

Page 9: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL CONFORM Extruded AZ31 Rods

From cast rods

Φ5 mm

From cast rods

Φ7 mm

From extruded rods

Φ5 mm

Meters long product successfully producedg p y pSurface finish depends on the feedstock, heating temperature & extrusion speedExcellent surface finish when extruded rods were used as feedstock

Produced by a Commercial CONFORM Machine Designed for Aluminum

Page 10: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL Grain Refinement

Feedstock~150 m

Near Surface~1.5 m

Center~2 m SEM

10 µm

2 m

Cross

Significant Grain Refinement: ~150 m to ~2 m

µ Cross Sections of

the Rod

Page 11: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Microstructure Characterization: High Resolution SEM

Grains in Submicrons

Near CenterNear Surface

Grains in Submicrons

Page 12: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Microstructure Characterization: SEM-EDS

A

A A B

B

Page 13: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Microstructure & Texture Characterization: EBSD

ED

Inverse Pole Figure Map: Extrusion DirectionInverse Pole Figure Map: Extrusion Direction

Near Center, Average Grain Size: ~1.0 m

Page 14: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL AZ31 Textures: CONFORM VS. ECAP

0001ED

0121

3121 0001

1102

<0110>

0001 ED 00012311 0121

ED0001

0110{0001}

EDmax=14.457Y

1110

Janecek et al, J. Mat. Sci. , 2010X

CONFORM,Near Center

Basal Prismatic Pyramidal

ED

0001

ED 0001 ED 0001 ED 0001

Contours: 1, 2, …, 10 Contours: 1, 2, …, 10 Contours: 1, 2, …, 10 Contours: 1, 2, …, 15

ExtrusionECAP-1 Pass

ECAP-4 Passes

ECAP-12 Passes

Page 15: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Microstructure & Texture Characterization: EBSD

ED

30 µm

Inverse Pole Figure Map: Extrusion Direction

Near Surface, Average Grain Size: ~0.92 m

Page 16: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL AZ31 Textures: CONFORM VS. ECAP

0001ED 0001

ED 0001

ED

0001

0121

3121 0001

1102

<0110>

2311 0121

EDmax=6.037YED

0001 0110{0001} 1110

Janecek et al, J. Mat. Sci. , 2010XCONFORM,Near Surface

Basal Prismatic Pyramidal

ED

0001ED 0001 ED 0001 ED 0001

Contours: 1, 2, …, 10 Contours: 1, 2, …, 10 Contours: 1, 2, …, 10 Contours: 1, 2, …, 15

ExtrusionECAP-1 Pass

ECAP-4 Passes

ECAP-12 Passes

Page 17: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Superplastic-like Deformation Achieved by one Pass CONFORM Extrusion

Strain rate: 3.3×10-4 s-1

T = 473 KTo Achieve Superplasticity in Mg Alloys

Strain rate:

Small Grain SizesUniform MicrostructurePreferred Orientations

12.7 mm

St a ate1.0×10-4 s-1 Relatively Low Strain Rates

Appropriate Deformation Temperature

3.1 mm

Extrusion CONFORM- 1 Pass ECAP: Multi-PassesGrain size ~15 m ~2 m ~0.7 m

C-axis ^ ED ~90 40~90 40~50C axis ED 90 40 90 40 50Elongation ~100% ~200% > 460%

Page 18: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Inhomogeneous Microstructure after 1 Pass CONFORM

Near CenterNear Surface Near CenterNear Surface

Multiple-pass processing: uniform microstructureHeat treating after CONFORM Optimization of the processing parameters

Page 19: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL Summary & Conclusions

Successfully Produced Long Wrought AZ31 Mg Alloy by CONFORM

Significant Grain Refinement from Cast Structure of ~150 µm to 1~2 µm

Superplastic-like Deformation Behaviour Observed in CONFORM Extruded Samples Observed in CONFORM Extruded Samples

Non-uniform Microstructure and Heterogeneous Texture in the Cross SectionHeterogeneous Texture in the Cross Section

An Alternative Forming Method to Mg Alloys

Page 20: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Thank YouThank You

Page 21: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL Microstructure Characterization: FIB

Significant Grain Refinement: ~150 m to ~1 m

Page 22: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL

Page 23: Grain Refinement of Magnesium Alloys by CONFORM: A ...coursenotes.mcmaster.ca/791_Fractures/He.pdf · What is Severe Plastic Deformation? ... A Continuous Severe Plastic Deformation

CANMET-MTL Future Work

Processing other Mg alloys by CONFORM

Microstructure characterization and

mechanical properties testingg

Heat treatment after CONFORM

Multipass CONFORM extrusion to produce Multipass CONFORM extrusion to produce

uniform & ultrafine grained

i t tmicrostructure

Texture measurements and analysis

Modeling the CONFORM process