摘要
采用Gleeble-3500热模拟试验机对AA7021铝合金在变形温度为350~490℃、应变速率为0.01~10 s^-1的热变形条件下进行热压缩试验。建立基于应变的本构方程以及材料热变形特征的热加工图,并对热加工图中安全区和失稳区的显微组织进行分析。结果表明,在安全区有形变诱导析出;在变形失稳区内,当变形温度较低、应变速率较高时,由于应变热效应的作用,形成了绝热剪切带。另外,在应变速率大于1 s^-1的区域中发现导致铝合金热加工性能变差的原因有局部流变、大粒子破碎脱粘、微观裂纹等。在热变形过程中,随着温度的升高,铝合金的动态软化机制由动态回复转向动态再结晶。AA7021铝合金在中温、高温热压缩过程中共存着多种软化机制,但动态回复占主导地位。
Athermal compression experiment for AA7021 aluminum under a temperature ranging from 350—490℃and a strain rate ranging from 0.01—10 s^-1 was carried out by using gleeble-3500 thermal simulation test machine.A strain-based constitutive equation and a thermal processing diagram of the thermal deformation characteristic of the material was established and the microstructure of the safety zone and the instability zone in the thermal processing diagram was analyzed.The results show that the deformation induced precipitation effect is found in the safety zone.In the deformation instability zone,when the deformation temperature became lower and strain rate became high,the adiabatic shear zone is formed due to the effect of strain heat.In addition,in the region where the strain rate is greater than 1 s^-1,the cause of deterioration of aluminum hot workability are found to be local rheology,large particle breakage,microcrack,etc.During the thermal deformation process,the dynamic softe-ning mechanism of aluminum changes from dynamic recovery to dynamic recrystallization as the temperature increase.AA7021 aluminum alloy coexists a variety of softening mechanism in the medium temperature and high temperature compression process,but dynamic recovery still dominates.
作者
仇鹏
王家毅
段晓鸽
蔺宏涛
陈康
江海涛
QIU Peng;WANG Jiayi;DUAN Xiaoge;LIN Hongtao;CHEN Kang;JIANG Haitao(Institute of Engineering and Technology,University of Science and Technology Beijing,Beijing 100083,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2020年第8期106-112,共7页
Materials Reports
基金
广西科技重大专项(桂科AA17202008-2)。
关键词
AA7021铝合金
本构方程
热加工图
形变诱导析出
软化机制
AA7021 aluminum alloy
constitutive equation
thermal processing diagram
deformation induced precipitation
softening mechanism
