Ti对近共晶铝镁硅合金热变行为的影响

Effect of titanium on hot deformation behavior of near eutectic Al-Mg-Si alloy

采用Gleebe-3500热模拟试验机在变形温度350℃~500℃,应变速率0.01s^(-1)、0.1s^(-1)、1s^(-1)和5s^(-1),最大变形量60%的条件下对近共晶Al-Mg-Si、Al-Mg-Si-Ti合金进行等温热压缩模拟研究。建立了两种近共晶合金的高温流变本构方程和热加工图,并结合EBSD微观组织分析了Ti对近共晶Al-Mg-Si合金高温流变行为的影响。研究结果表明,可用含Arrhenius项的Z参数描述两种合金高温变形时的流变行为;并基于热加工图得出Al-Mg-Si合金优化的工艺参数为变形温度475℃~500℃,变形速率0.01s-1,Al-Mg-Si-Ti合金优化的工艺参数为变形温度450℃~475℃,变形速率0.1s^(-1);同时发现含Ti第二相颗粒会在高温塑性变形过程中阻碍位错运动,抑制动态再结晶软化,提高合金高温流变应力和形变激活能。

The high-temperature deformation behaviors of near eutectic Al-12.5Si-0.5Mg and Al-12.5Si-0.5Mg-0.1Ti were studied by hot compressive tests on a Gleebe-3500 thermal simulation machine in the temperature range of 350℃500℃ and with the strain rate of 0.01s-1,0.1s-1,1s-1 and 5s-1 with maximum strain of 60%.The high-temperature deformation behaviors of two near eutectic Al-Mg-Si alloy were described by constitutive equations and processing maps.Based on EBSD analysis,the effect of Ti mirco particles on the high-temperature deformation behaviors of near eutectic Al-Mg-Si alloys was studied.The results show that the relation between steady flow stress and strain rate and temperature can be described with parameter Z which contains Arrhenius item.On the basis of the processing maps,the optimum processing conditions of Al-Mg-Si and Al-Mg-Si-Ti alloys are in the temperature range of 475℃500℃ with the strain rates around 0.01s-1 and 450℃475℃ with strain rates of 0.1s-1,respectively.It was found that Ti mirco articles hinder the movement of dislocation,resist dynamic recrystallization softening,and increase high-temperature flow stress and activity energy during hot deformation.