1. Background
Mg AZ31B sheet alloy has advantages of low density, high strength and
high stiffness. However, it has limited formability at room temperature,
and unknown behavior at complex forming conditions, especially in the
thermoforming process.
The objective of this research is:
1) Design and optimize test devices for elevated-temperature
tension / compression (T / C) of sheet metal alloys
2) Measure T / C plastic hardening curves for Mg AZ31B sheet
3) Develop constitutive laws for Mg AZ31B sheet alloys
(0.1/s-10-4/s, 150oC-300oC)
4) Simulate thermo-assistant deep drawing of Mg AZ31B, enhancing
formability using non-isothermal heating strategies 1

2. Sheet Tension / Compression Test
Room Temperature
G=36.8mm
B=50.8mm
W=15.2mm
L>3mm
Side Force
Mg AZ31B, O-temper, 3.2mm
Laser extensometer
Boger et al., Int. J. Plast., 2005
Lou et al., Int. J. Plast., 2007 2

3. Sheet Tension / Compression Test
Elevated Temperature 3

4. Sheet Tension / Compression Test
Elevated Temperature 4

5. Constitutive Equations, 150oC-300oC:
Mg AZ31B 1mm sheet
M1 <7MPa>:
M2opt <4MPa>:
<0.03>
<0.98>
<0.49> 5

6. Thermo Deep Drawing Axisymmetric Uniform Temperature: 150oC-300oC:
Punch:
t = 1.0 mm
R = 60 mm
Blank holder
Die
R = 5 mm
25 mm
Uniform Temperature:
150oC-300oC:
Axisymmetric
Material Model: M2opt
Friction coeffcient = 0.08
Fix the positions of blank holder and die
Finer Mesh in the corner of punch and die
Velocity of punch = 10, 1, and 0.1 mm/s
hto air = 20 W/m2K
300oC 6

7. Thermo Deep Drawing R=60mm, Punch speed = 1mm/s
Failure criteria: thickness strain = -0.2
150oC-300oC
50 mm
150oC
14 mm
Necking
LDR = Di/Df (Depth)
10mm/s
1mm/s
0.1mm/s
150oC
1.9 (38mm)
1.9 (37mm)
200oC
250oC
1.8 (36mm)
300oC
1.8 (35mm)
150oC-200oC
2.3 (58mm)
2.2 (49mm)
150oC-250oC
2.4 (63mm)
2.6 (72mm)
2.6 (73mm)
150oC-300oC
3.2 (121mm)
3.2 (123mm)
3.3 (125mm)
*Diameter of finished cup: Df = 55.2mm 7

8. Conclusions Develop high-temperature T/C device
Temperature range: RT - 450oC
DT (Gage Length) < 8oC
Heating time = 10 minutes for 250oC
High Temperature T/C testing of Mg AZ31B sheet:
Inflected flow (twinning) disappears between 130oC - 140oC
Constitutive equations for Mg AZ31B sheet:
Experiments, numerical fitting and FEA verification
150oC - 300oC, /s, standard deviation = 4MPa
Thermo-assistant deep drawing:
Non-isothermal heating improve the LDR from 1.9 to 3.3 8

9. Mg AZ31B Sheet Formability: Experiment and Simulation
K. Piao and R. H. Wagoner
Department of Materials Science and Engineering, The Ohio State University