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对7A09半连续铸造铝合金进行了热模拟试验,研究了该合金在300、350、400℃,应变速率0.01、0.1、1、5 s~(-1),变形量50%条件下的流变行为。结果表明:该合金在变形温度300℃并且应变速率0.01 s~(-1)时具有明显的峰值应力,应力-应变曲线具有加工硬化、应变软化和稳态流变三个阶段;变形温度达到400℃时,曲线无明显峰值应力。通过计算求得应力水平参数α、应力指数n、变形激活能Q和结构因子A的具体值。应变速率和变形温度对于合金流变应力的影响可用Arrhenius方程和包含Zener-Hollomom参数的关系式表示。热加工图表明该合金具有较低的能量耗散率,高温变形的主要软化机制为动态回复。
The thermal simulation of 7A09 semi-continuous casting aluminum alloy was carried out. The rheological behavior of the alloy at 300,350,400 ℃, strain rate of 0.01,0.1,1,5 s ~ (-1) and deformation of 50% behavior. The results show that the alloy has obvious peak stress at deformation temperature of 300 ℃ and strain rate of 0.01 s ~ (-1), and the stress-strain curve has three stages of work hardening, strain softening and steady state rheology. When the deformation temperature reaches 400 ℃, the curve has no obvious peak stress. The specific values of stress level parameter α, stress index n, deformation activation energy Q and structure factor A are obtained by calculation. The effect of strain rate and deformation temperature on the flow stress of the alloy can be expressed by the Arrhenius equation and the equation containing the Zener-Hollomom parameters. The hot working diagram shows that the alloy has lower energy dissipation rate and the main softening mechanism of high temperature deformation is dynamic recovery.