Influence of strain rate on microstructure and formability of AZ31B magnesium alloy sheets
(1. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 40004, China;
3. Chongqing Research Center for Advanced Materials,Chongqing Academy of Science and Technology, Chongqing 401123, China)
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 40004, China;
3. Chongqing Research Center for Advanced Materials,Chongqing Academy of Science and Technology, Chongqing 401123, China)
Abstract: The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10-4, 10-3, 10-2, 10-1 s-1 at 200 °C. The results show that the volume fraction of dynamic recrystallization grains increases and the original grains are gradually replaced by recrystallization grains with the strain rate decreasing. A larger elongation and a smaller r-value are obtained at a lower strain rate, moreover the erichsen values become larger with the strain rate reducing, so the formability improves. This problem arises in part from the enhanced softening and the coordination of recrystallization grains during deformation.
Key words: AZ31B magnesium alloy; strain rate; dynamic recrystallization; formability