(1. 上海交通大学 材料科学与工程学院，上海 200240；
2. 上海交通大学 轻合金精密成型国家工程研究中心和金属基复合材料国家重点实验室，上海 200240；
3. 上海宝钢研究院，上海 200940)
摘 要: 采用Thermecmastor-Z 热模拟试验机在变形温度为200~520 ℃、应变速率为2~60 s-1 条件下对AZ31B 镁合金厚板进行热压缩变形试验，压缩变形量为60%。结合变形后的微观组织以及热压缩真应力-真应变曲线，分析应变速率和变形温度等工艺参数对其微观组织演变的影响。结果表明：当变形温度高于320 ℃时，AZ31B 镁合金的真应力-真应变曲线呈现典型的动态再结晶特性。当应变速率一定时，流变应力随温度升高而降低；当变形温度一定时，流变应力在高温低应变速率(低于15 s-1)下随应变速率增大而增大。变形后的微观组织显示，压缩变形过程中发生了明显的动态再结晶，动态再结晶体积分数随应变速率的增加而增大。另外，变形组织的均匀性受变形温度的影响十分显著。在热压缩实验的基础上，在温度为300~330 ℃时对板材进行单道次大压下量的热轧，获得的板材具有均匀细小的晶粒及优异的力学性能。
关键字: AZ31B 镁合金；高应变速率；压缩变形；微观组织；动态再结晶
（1. School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;
2. National Engineering Research Center of Light Alloys Net Forming and
State Key Laboratory of Metal Matrix Composite,Shanghai Jiao Tong University,Shanghai 200240,China;
3. Shanghai Baosteel Research Institute,Shanghai 200940,China）
Abstract:The compression deformation behaviors of AZ31B thick plate at different deformation temperatures of 200-520 ℃ and high strain rates of 2-60 s-1 were studied by using Thermecmastor-Z hot simulation equipment with a strain of 60%. The influence of deformation temperature and strain rate on the microstructure evolution based on the microstructures after deformation and true stress-true stain curve after hot compression was investigated. The results show that true stress-true strain curve is a normal shape for hot working with dynamic recrystallization when deformation temperature is higher than 320 ℃. And the flow stress decreases with increasing temperature at a given strain rate,while it increases with increasing strain rate at a given temperature and a strain rate lower than 15 s-1. The microstructure observation also suggests that dynamic recrystallization takes place obviously during the deformation process. The volume fraction of dynamic recrystallization grains increases with increasing strain rate. In addition,distinct distribution of gains exists in the samples deformed at various temperatures. Based on the hot compression experiment results,AZ31B rolling sheet was processed at 300-330 ℃ and at large reduction per pass. The obtained AZ31B sheet shows fine grain size and excellent mechanical properties.
Key words: AZ31B Mg alloy; high strain rate; compression deformation; microstructure; dynamic recrystallization
