Al-Mg-Si合金热压缩变形的流变应力方程

Flow stress equation for hot compression deformation of Al-Mg-Si alloy

为了给制定和优化热加工工艺参数提供理论依据,采用Gleeble-1500热模拟机研究了含锆Al-Mg-Si合金在变形温度为653～803 K、变形速率为0.01～10 s-1条件下的热压缩变形的流变应力行为,并通过回归法建立材料变形的流变应力数学模型.结果表明:该合金为正应变速率敏感材料,真应力-真应变曲线存在明显的稳态流变特征;流变应力随着变形速率的增加以及变形温度的降低而增加;在较低变形温度条件下,真应力-真应变曲线为动态回复曲线;在较高变形温度条件下真应力-真应变曲线为动态再结晶曲线.该合金流变应力σ可用包含Arrhenius项的Zener-Hollomon参数的函数来描述,式中A、α和n的值分别为1.89×1010s-1、0.024 MPa-1和7.46,热变形激活能Q为166.85 kJ/mol.

In order to provide the theoretical basis for the establishment and optimization of technological parameters for hot working process,the flow stress behavior of the Al-Mg-Si alloy containing Zr element during hot compression deformation was studied with Gleeble-1500 thermal-mechanical simulator at temperatures from 653 K to 803 K and deformation rates from 0.01 s-1 to 1 s-1.In additon,a mathematical model for the flow stress of material deformation was established with regression method.The results show that the alloy is a material sensitive to normal strain rate,and the obvious steady-state rheological feature exists on the true stress-true strain curves.With increasing the deformation rate and decreasing the deformation temperature,the flow stress increases.The true stress-true strain curves are dynamic recovery curves at lower deformation tempertures,and are dynamic recrystallization curves at higher deformation temperatures.The flow stress σ of the alloy can be described by the Zener-Hollomon parameter including Arrhenius term,where the values of parameters A,α and n are 1.89×1010 s-1,0.024 MPa-1 and 7.46 respectively.Moreover,the activation energy Q for the hot deformation is 166.85 kJ/mol.