Mg AZ31B Sheet Formability: Experiment and Simulation

1
Mg AZ31B Sheet Formability Experiment and
Simulation K. Piao and R. H. Wagoner Department
of Materials Science and Engineering, The Ohio
State University
Mg AZ31B sheet alloy has advantages of
low density, relatively high strength and high
stiffness. However, it has limited formability at
room temperature, and unknown behavior at
complex forming conditions, especially in the
thermo-assistant forming 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
Sheet Tension / Compression Test Room Temperature
Sheet Tension / Compression Test Elevated
Temperature
Sheet Tension / Compression Test Elevated
Temperature
Background
Mg AZ31B, O-temper, 3.2mm

Critical temperature is between 130oC to 140oC



Boger et al., Int. J. Plast., 2005
Lou et al., Int. J. Plast., 2007
1
3
4
2
Constitutive Equations, 150oC-300oC Mg AZ31B 1mm
sheet
Conclusions
Thermo-assistant Deep Drawing
Thermo-assistant Deep Drawing

• Develop high-temperature T/C device
• Temperature range RT - 450oC
• DT (Gage Length) lt 8oC
• Heating time 10 minutes for 250oC

R60mm, Punch speed 1mm/s Failure criteria
thickness strain -0.2

150oC-300oC
M1 lt7MPagt
Uniform Temperature
150oC

• 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, 0.1-10-4/s, standard deviation
  4MPa

LDR Di/Df (Depth) 10mm/s 1mm/s 0.1mm/s
150oC 1.9 (38mm) 1.9 (37mm) 1.9 (37mm)
200oC 1.9 (38mm) 1.9 (37mm) 1.9 (37mm)
250oC 1.9 (38mm) 1.9 (37mm) 1.8 (36mm)
300oC 1.9 (38mm) 1.9 (37mm) 1.8 (35mm)
150oC-200oC 2.3 (58mm) 2.2 (49mm) 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)
M2opt lt4MPagt
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

lt3.7MPagt

• Thermo-assistant deep drawing
• Non-isothermal heating improve the LDR from 1.9
  to 3.3

lt0.03gt
150oC
lt0.49gt
ht_s 3000 W/m2K
lt0.98gt
7
8
5
6
Diameter of finished cup Df 55.2mm