复合变形应变状态对AZ31镁合金组织性能的影响

Effect of Strain State at Compound Deformation on Microstructure and Properties of AZ31 Magnesium Alloy

分析了压痕-压平复合变形工艺特点及应力与应变状态。研究了压痕-压平复合变形时应变状态对镁合金材料孪晶组织的影响。结果表明,应变状态是镁合金材料产生孪晶的主要因素。拉伸变形区的组织产生了少量的孪晶,晶粒细化不明显;压缩变形区的组织产生了很多细小的压缩孪晶,晶粒细化明显。压痕-压平复合变形产生了压缩变形→孪晶组织形成→发生动态再结晶→孪晶消失→晶粒细化的组织演变过程,形成分布均匀的细小的晶粒组织,从而使镁合金板料的组织性能得到有效改善。压痕-压平复合变形使镁合金板材的形核率的增加速率大于晶粒长大率的增加速率,发生了完全动态再结晶后,晶粒得到进一步细化。

The characteristics and stress state-strain rate of indentation-flatten compound deformation technology（IFCDT）were analyzed.Effects of strain state of IFCDT on microstructure of AZ31 magnesium alloy were described.The results show that the strain state is the main factor influencing the twin grain of magnesium alloy.In tensile deformation area,a small amount of twin grain can be observed,while the grain refinement can be ignored.In the compression deformation area,fine compression twins occur,and the grain size is refined obviously.During indentation-flat compound deformation（IFCDT）,tensile deformation and compression deformation（or compression deformation and tensile deformation）are changed alternatively.The microstructure evolution law of AZ31 magnesium alloy deformed by IFCDT is that compression strain→twins formation→dynamic recrystallization occurs→twin disappear→grain refine.Grains are refined with uniformly distribution.Microstructure of magnesium alloy sheet is improved.The mechanism of improving performance of the magnesium alloy by IFCDT is that the alternation change between tensile deformation and compression deformation resulted to nucleation rate is the greater than grain growth rate,so complete dynamic recrystallization occurs,and grain is refined greatly.