不同热变形条件下Al-Zn-Mg-Cu包铝板的组织演变

摘要

Al-cladded Al-Zn-Mg-Cu sheets were compressed up to 70％ reduction on a Gleeble-3500 thermo-mechanical simulator with temperatures ranging from 380 to 450 ℃ at strain rates between 0.1 and 30 s 1.The microstructures of the Al cladding and the Al-Zn-Mg-Cu matrix were characterized by electron back-scattered diffiraction (EBSD) and X-ray diffraction (XRD).The microstructure is closely related to the level of recovery and recrystallization,which can be influenced by deformation temperature,deformation pass and deformation rate.The level of recovery and recrystallization are different in the Al cladding and the Al-Zn-Mg-Cu matrix.Higher deformation temperature results in higher degree of recrystallization and coarser grain size.Static recrystallization and recovery can happen during the interval of deformation passes.Higher strain rate leads to finer sub-grains at strain rate below 10 s-1;however,dynamic recovery and recrystallization are limited at strain rate of 30 s-1 due to shorter duration at elevated temperatures.%利用Gleeble-3500热模拟试验机对Al-Zn-Mg-Cu包铝板进行热变形,采用EBSD和XRD对不同变形条件下的Al-Zn-Mg-Cu基体和包铝层显微结构进行表征,其变形条件为变形量70％、温度380～450℃、应变速率0.1～30 s-1.结果表明,变形温度、道次和变形速率直接影响样品的回复和再结晶过程,从而进一步影响其显微结构.在包铝层和Al-Zn-Mg-Cu基体中回复和再结晶的程度有所区别.较高的变形温度导致较高程度的再结晶以及较大的晶粒尺寸.在多道次变形中的停留时间内会发生静态再结晶.当应变速率低于10 s-1时,随着应变速率的增大,出现较多细小的亚晶组织;然而,在30 s-1的大应变速率条件下,试样在变形温度下停留时间较短,导致动态回复及再结晶程度受限.