Abstract—The true stress-strain curves of AZ31B magnesium alloy sheet were obtained by using the uniaxial tensile tests at temperatures ranging from 50℃to 300 ℃ and initial strain rates ranging from 0.001/s to 0.1/s. The effects of temperature and strain rate on the flow stress were analyzed. The results show that the flow stress decreases and the elongation at fracture increases with increasing temperature and decreasing strain rate, and the formability is improved obviously. Two mathematical models were developed to determine the flow stress at hot deformation condition:(1) the model based on the Fields-Backofen equation, and (2) the model based on a natural exponential form whose exponent is a quadratic function. By comparison of the calculated results with experimental data, it was proved that the flow stresses calculated by the Fields–Backofen model only give a good fit to the measured ones at the work-hardening stage, but it cannot describe the softening behavior after the peak stress. Whereas, the exponential model does not only accurately reflect work hardening before the peak stress, but approaches more closely at the dynamic softening stage of the flow stress than that of the Fields–Backofen model.

Index Terms—AZ31B magnesium alloy, uniaxial tensile, dynamic recrystallization (DRX), flow stress, mathematical model.

W.-J. Li, G.-Q. Zhao, and X.-W. Ma are with Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Shandong, Jinan 250061, China, (email: liwj@sdu.edu.cn, zhaogq@sdu.edu.cn, maxinwu@sdu.edu.cn).
J. GAO is with School of Mechanical, Electrical and information Engineering, Shandong University at Weihai, Shandong, Weihai 264209, China (email: dshdgj@sdu.edu.cn).

Cite: Li Wen-Juan, Zhao Guo-Qun, Ma Xin-Wu, and Gao Jun, "Flow Stress Characteristics of AZ31B Magnesium Alloy Sheet at Elevated Temperatures," International Journal of Applied Physics and Mathematics  vol. 2, no. 2, pp. 083-088, 2012.