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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 19    Special 3    December 2009

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Dynamic softening behaviors of 7075 aluminum alloy
QUAN Guo-zheng(权国政)1, LIU Ke-wei(刘克威)1, ZHOU Jie(周 杰)1, CHEN Bin(陈 斌)2

1. School of Material Science and Engineering, Chongqing University, Chongqing 400044, China;
2. School of Resources and Environmental Science, Chongqing University, Chongqing 400044, China

Abstract:The dynamic softening behaviors during hot deformation of 7075 aluminum alloy were studied by isothermal hot compression tested at temperatures of 250, 300, 350, 400 and 450 ℃ and strain rates of 0.01, 0.1, 1 and 10 s−1 on Gleeble1500. The results show that the temperature changes have a significant effect on the dynamic softening rate. It is indicated that the considerable dynamic softening rate associated with dynamic recrystallization leads flow stress value decreasing gradually. A group of coefficients needed by the phenomenological constitutive model containing a softening ratio item were calculate d by the multiple linear regression method. The optical microstructures show that the grains of billets compressed become more and more refined with strain rate increasing as well as the degree of dynamic softening and work-hardening higher. The phenomenological constitutive description of 7075 aluminum alloy can accurately describe the relationships among flow stress, temperature, strain rate, strain and dynamic softening, and offer the basic model for plastic forming process simulation.

 

Key words: 7075 aluminum alloy; flow stress; constitutive model; softening

ISSN 1672-7029
CN 43-1423/U

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