A356铝合金的高温流变行为及本构模型研究

Study on high-temperature rheological behavior and constitutive model for A356 aluminum alloy

A356铝合金的高温流变特性和本构模型对其应力状态起着重要的作用,为铝合金流变成形过程的有限元模拟奠定了重要的基础。从A356铝合金轮毂铸造坯料上制取拉伸试样,利用Instron 3369型实验机进行等温拉伸实验,实验温度为300~375℃,应变速率为0.001~0.1 s^(-1)。由此得到的真应力-真应变曲线表明,温度和应变速率等热力学条件对材料的流变应力的影响显著。基于真应力-真应变曲线,建立了基于位错密度理论的物理模型来表征不同热力学条件下的流变应力。将模型预测值与实验值进行对比,并进行误差分析。结果表明,所建立的物理模型能够较准确地预测A356铝合金的高温拉伸流变行为。

The high-temperature rheological behaviour and the constitutive model of A356 aluminum alloy play an important role on its stress state, which lays a significant foundation for the finite element simulation of aluminum alloy during the rheological forming process. Therefore, the tensile specimens were prepared from A356 aluminum alloy wheel hub casting billet, the isothermal tensile experiments were conducted by test machine Instron 3369 at the experimental temperature of 300-375 ℃ and the strain rate of 0.001-0.1 s^(-1). The obtained true stress-true strain curves show that the rheological stress of material is significantly affected by thermodynamic conditions such as temperature and strain rate. Based on the true stress-true strain curve, a physical model based on dislocation density theory was established to characterize the rheological stress under different thermodynamic conditions. The predicted value of the model was compared with the experimental data, and the error analysis was carried out. The results show that the established physical model can accurately predict the high-temperature tensile rheological behaviour of A356 aluminum alloy.