航天用7055高强铝合金热变形行为及热加工图

Hot Deformation Behavior and Hot Working Diagram of 7055 High Strength Aluminum Alloy for Aerospace

利用高温压缩试验研究航天用7055高强铝合金在温度为330、380、430、480℃,应变速率为0.001、0.01、0.1、1s^(-1)条件下的高温流变应力的变化。根据高温压缩试验数据,借助线性回归方法,拟合出7055高强铝合金的峰值流变应力本构方程和稳态流变应力本构方程。结果表明,在热压缩变形的开始阶段,7055高强铝合金的流变应力随着应变量的增加迅速增大至峰值,然后由于产生应变软化,其真应力随着应变量的增加降低,直至进入稳态流变阶段。当应变速率一定时,流变应力随着变形温度的升高而降低;当变形温度一定时,流变应力随着应变速率的增加而增大。建立了真应变为0.2时的热加工图,在成形温度为330~410℃,应变速率为0.001~0.05s^(-1)的区域,功率耗散系数大于20%,此范围为航天用7055高强铝合金较合理的工艺参数。

Through high temperature compression experiment,the variation of high temperature rheological stress of 7055 high strength aluminum alloy for aerospace was investigated under different temperatures(330,380,430 and 480℃)and strain rates(0.001,0.01,0.1and 1s^(-1)).According to the high temperature compression experimental data,with the help of linear regression method,the peak flow stress constitutive equation and steady flow stress constitutive equation of 7055 high strength aluminum alloy were established.The results indicate that at the beginning of hot compression deformation,the flow stress of 7055 high-strength aluminum alloy is increased rapidly to the peak value with the increase of stress,then the true stress is decreased with the increase of stress variable due to strain softening until the steady-state flow stage.When the strain rate is constant,the flow stress is decreased with the increase of deformation temperature.When the deformation temperature is constant,the flow stress is increased with the increase of strain rate.Finally,the hot working diagram with true strain of 0.2 was established.In the region of forming temperature of 330~410℃and strain rate of 0.001~0.05s^(-1),the power dissipation coefficient is more than 20%,which is the reasonable process parameters of 7055 high strength aluminum alloy for aerospace.