电弧增材制造2219铝合金热变形组织演变及本构方程

Microstructure evolution and constitutive equation of wire arc additive manufactured 2219 aluminum alloy during hot deformation

采用热压缩方法研究了电弧增材制造2219铝合金的热变形行为,变形温度为360~510℃,应变速率为0.01~10 s^(-1)。分析了温度和应变速率对流变应力和微观组织的影响,采用Zener-Hollomon参数的双曲正弦函数建立了电弧增材制造2219铝合金热变形本构方程。结果表明,电弧增材制造2219铝合金热压缩峰值应力随温度的升高和应变速率的降低而逐渐降低。电弧增材合金在420℃及以下温度仅发生滑移变形,450℃及以上发生动态再结晶,480℃为最佳锻造温度,发生完全动态再结晶,可有效细化增材晶粒。本构方程以动态再结晶温度(450℃)为临界点分为两段,动态再结晶温度以下变形激活能为212.53 kJ·mol^(-1),动态再结晶温度以上为163.37 kJ·mol^(-1)。沿晶界分布的共晶θ相在热压缩过程中发生破碎和固溶,变形温度越高或应变速率越小,固溶程度越高。

The hot deformation behavior of wire arc additive manufactured(WAAM)2219 aluminum alloy was studied by hot compression method,and the deformation temperature was 360-510℃,the strain rate was 0.01-10 s^(-1).The effects of temperature and strain rate on the flow stress and microstructure were analyzed.The hot deformation constitutive equation of WAAM 2219 aluminum alloy was established with hyperbolic sinusoid function of Zener-Hollomon parameter.The results show that the hot compression peak stress of WAAM 2219 aluminum alloy decreases gradually with the increase of temperature and the decrease of strain rate.For WAAM alloy,only sliding deformation occurs at 420℃and below,and dynamic recrystallization occurs at 450℃and above.480℃is the best forging temperature and complete dynamic recrystallization occurs,which can effectively refine the additive grains.The constitutive equation is divided into two stages taking the dynamic recrystallization temperature(450℃)as the critical point.The deformation activation energy is 212.53 kJ·mol^(-1)below the dynamic recrystallization temperature and 163.37 kJ·mol^(-1)above the dynamic recrystallization temperature.The eutecticθphases distributed along the grain boundaries broke and are solid dissolved in the process of hot compression.The higher the deformation temperature is or the small the strain rate is,the higher the solid solution degree is.