摘要
通过光学显微镜(OM)及电子背散射衍射分析技术(EBSD)研究室温多向锻压(MDF)下AZ31镁合金在473K下的静态再结晶(SRX)行为,对高密度孪晶组织的再结晶行为、显微组织演变、再结晶动力学及退火初期再结晶晶粒取向进行研究。结果表明:室温多向锻压AZ31镁合金的累积应变量越大,孪晶密度越高,退火过程中越容易发生再结晶。不管试样累积应变量高还是低,硬度曲线在退火过程中均分为3个阶段,且第一阶段硬度值均基本不变,但低累积应变量试样比高累积应变量试样更迟进入第二阶段,进入第三阶段低累积应变量试样硬度继续呈下降趋势而高累积应变量试样硬度基本处于稳态。高累积应变量试样能用JMAK方程很好地描述退火组织的再结晶过程,但低累积应变量试样却不能。退火初期,再结晶晶粒与母相仍然保持孪晶关系,且其基面取向与最终压缩方向垂直或平行。
Static recrystallization (SRX) behavior of a wrought AZ31 magnesium alloy at 473 K was studied after multi-directional forging (MDF) using optical microscopy (OM) and electron backscattering microscopy (EBSD). Effects of introduced high-density twins on SRX behavior, microstructural development, SRX kinetics and initial orientation of SRX grains during the isothermal annealing were investigated. The results show that SRX can be accelerated through high-density twins introduced by high cumulative strain. The variation of hardness (HV) with annealing time of wrought samples includes three periods irrespective of prior strain: HV hardly changes in the early stage of annealing and drops rapidly in the middle stage until it finally approaches the fully annealed value. At high cumulative strain, variation of HV proceeds earlier into the middle stage and then reaches a steady value while HV keeps dropping gradually in the final stage at low cumulative strain. The relationship between recrystallization volume fraction and annealing time can be perfectly described by JMAK equation at high cumulative strain but cannot at low cumulative strain. SRX grains exhibit almost same orientations of prior twins with its basal plane aligned parallel and perpendicular to the forging direction of the last pass.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2015年第11期3051-3059,共9页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(51474241
51071182)
国家重点基础研究发展计划资助项目(2013CB632204)
关键词
AZ31镁合金
孪晶
静态再结晶
再结晶动力学
晶粒取向
AZ31 magnesium alloy
twin
static recrystallization
recrystallization kinetics
grain orientation
