AZ31镁合金铸轧和常规轧制板的变形组织及形变特征

在变形温度为150～400 ℃、应变速率为0.3～0.000 3 s~(-1)条件下,在Gleeble1500热模拟机上采用等温拉伸试验对AZ31镁合金铸轧和常规轧制板的高温塑性及组织演变进行研究.结果表明:两种AZ31镁合金板的峰值应力和峰值应变均随着变形温度的降低和应变速率的增加而逐渐增大.铸轧板的应变硬化指数和应变速率敏感系数均大于常规轧制板的.在高温低应变速率变形条件下,铸轧板的晶界滑移引起的空洞尺寸、体积分数和密度均大于常规轧制板的.低应变速率下拉伸变形后的动态再结晶晶粒尺寸随温度的升高逐渐增加;不同变形条件下铸轧板的晶粒尺寸均小于常规轧制板的;再结晶晶粒尺寸和Z参数呈幂律关系.

Deformation microstructure and characteristics of cast-rolling and normal rolling AZ31 magnesium alloy sheets

The elevated temperature plasticity and microstructure evolution of cast-rolling and normal rolling AZ31 magnesium alloy sheets were analyzed by Gleeble1500 using tension test with deformation temperature of 150-400 ℃ and strain rate of 0.3-0.000 3 s~(-1). The results show that the peak stress and peak strain of cast-rolling and normal rolling AZ31 magnesium alloys both increase with decreasing the deformation temperature and increasing the strain rate. The strain hardening exponent value and strain rate sensitivity value of cast rolling sheet are larger than those of normal rolling sheet. Cavity size, volume fraction and density of cast-rolling sheet caused by grain boundary sliding under deformation condition of high temperature and low strain rate are bigger than those of normal rolling sheet. The dynamic recrystallization grain size deformed in low strain rate increases with increasing the deformation temperature. The dynamic recrystallization grain size of cast rolling sheet is less than that of normal rolling sheet. The dynamic recrystallization grain size has power law relation with Z parameter.