Microstructures and Hardness of Non-isothermal Deep Drawn AZ31

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Microstructures and Hardness of Non-isothermal Deep Drawn AZ31 Powered By Docstoc
					Microstructures and Hardness of Non-isothermal Deep Drawn AZ31 Magnesium Sheets

Tyng-Bin Huang, and Yung-An Tsai Department of Mechanical Engineering, St. John's University, R.O.C. Abstract: The commercial FEM code MSC Superform was employed to simulate the deep drawing processes of AZ31
magnesium alloy in this study. The temperature and strain distributions of the deep drawn cups at various forming temperatures were determined from simulations. Circular cup drawing experiments were performed to obtain the temperature and thickness distributions of the drawn cups at various forming temperatures. Two surface thermocouples were used to measure the temperature distributions of drawn cups. Thickness and temperature distributions obtained from experiments were used to validate the FEM simulation results. The microstructure and mechanical property (Vickers Hardness) of deep drawn cup with AZ31 magnesium alloy were conducted at various temperatures to investigate the effect of dynamic recrystallization (DRX) on the hardness after drawn. The fine dynamically recrystallized grains are observed at forming temperature higher than 200℃. The grain size becomes larger at higher forming temperature. The hardness of the drawn cup becomes lower due to dynamic recrystallization which offset the effect of strain hardening
Ø55mm 100℃ Ø60mm Ø85mm 150℃ 200℃ Ø95mm 230℃ Ø100mm Ø95mm 260℃ 300℃

LDR 1.45

LDR 1.58

LDR 2.24

LDR 2.5

LDR 2.63

LDR 2.5

Drawn cup at various forming temperatures

non-isothermal deep drawing system

(A)

(B)

Hardness distribution of drawn cup forming at 200℃, strain and temperature distribution just after forming by FEM simulation (D) (C) Optical microstructure of drawn cup in flange area forming at (A) 150℃ (B) 200℃ (C) 260℃ (D) 300℃


				
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posted:6/30/2009
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