铸态Mg-2Y-0.8Mn-0.6Ca-0.5Zn镁合金热变形行为研究

Research on Hot Deformation Behavior of As-cast Mg-2Y-0.8Mn-0.6Ca-0.5Zn Magnesium Alloy

用Gleeble3500热模拟试验机对铸态Mg-2Y-0.8Mn-0.6Ca-0.5Zn镁合金进行热压缩变形试验,热变形温度和应变速率分别为375~450℃和0.001~5 s^(-1),利用试验数据绘制了真应力-应变曲线,并构建了双曲线正弦函数的本构方程和热加工图,同时分析了不同热变形温度和应变速率下材料的微观组织变化。铸态Mg-2Y-0.8Mn-0.6Ca-0.5Zn镁合金的热压缩变形激活能Q=230.32 kJ/mol,应力指数n=4.348,预测理想热变形温度和应变速率区域分别为410~450℃、0.03~0.25 s^(-1),该变区域功率耗散系数为30%~38%。热加工图中热变形稳定区域再结晶晶粒分布均匀,流变失稳区热变形再结晶晶粒分布不均匀。

Gleeble3500 thermal simulation testing machine was used to conduct hot compression deformation test on as-cast Mg-2 Y-0.8 Mn-0.6 Ca-0.5 Zn magnesium alloy.The hot deformation temperature and strain rate were 375—450℃and 0.001—5 s^(-1)respectively.The true stress-strain curve was drawn by using the test data.And the constitutive equation and thermal processing diagram of the hyperbolic sine function were constructed.At the same time,the microstructure changes of the materials after different thermal deformation temperatures and strain rates were analyzed.The activation energy and the stress index of hot compression deformation of the as-cast Mg-2 Y-0.8 Mn-0.6 Ca-0.5 Zn magnesium alloy were Q=230.32 kJ/mol and n=4.348 respectively.The predicted ideal thermal deformation temperature and strain rate region of as-cast Mg-2 Y-0.8 Mn-0.6 Ca-0.5 Zn magnesium alloy are respectively 410—450℃and 0.03—0.25 s^(-1),and the power dissipation coefficient of this variable region is 30%—38%.In the thermal processing diagram,the distribution of recrystallized grains in the thermal deformation stable region is relatively uniform,and the distribution of thermal deformation recrystallized grains in the rheological instability region is uneven.