中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 16 No. 2 April 2006 |
（1.College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
2.Department of Mechanical Engineering,Chongqing University of Science and Technology, Chongqing 400050, China ）
Abstract: Superplastic deformation mechanism of AZ31B magnesium alloy sheet was investigated. Maximum elongation of 216% and strain rate sensitivity of 0.36 were obtained at 723 K and a strain rate of 1×10−3s−1. It is found that dynamic recrystallization occurs at the early deformation stage, and that grain boundary sliding is the dominant deformation mode of superplastic AZ31B sheet, whose fracture is due to the growth and interlinkage of cavities nucleated at grain boundary. A cavity growth model was established, and damage characteristic parameters as well as the critical value of damage variable were identified so as to provide a theoretical ground on which the plastic forming technology of magnesium alloy sheet can be optimized.
Key words: AZ31B magnesium alloy; superplasticity; superplastic instability; strain sensitivity; cavity evolution; damage
