基于应变修正Arrhenius模型的Mg-3Al-3Sn-0.3Mn合金热加工图研究

Processing Maps of Mg-3Al-3Sn-0.3Mn Alloy Based on the Strain-compensated Arrhenius Model

目的以Mg-3Al-3Sn-0.3Mn(ATM3303)合金为研究对象,研究了一种使用少量基础实验数据,获得高精度低成本的热加工图的方法。方法利用少量热压缩实验获取ATM3303合金的真应力-应变曲线,根据应变修正的Arrhenius模型来分段拟合本构方程。根据本构方程可计算更多力学数据,以计算所得数据结合实验数据构建拓展的热加工图;将该拓展热加工图与基于实验数据的普通热加工图进行比较,通过验证实验判别2张热加工图的精度。结果相较于普通热加工图,经本构方程优化的拓展热加工图内,流变失稳区的面积有所减小。普通热加工图内的部分加工失稳窗口,在拓展热加工图内被预测为安全区。热挤压实验证实,ATM3303合金可在该工艺参数窗口下安全加工。在基础实验条件外,本构方程优化的热加工图预测了一个失稳区,实验显示,ATM33303合金在该失稳区进行热挤压会形成粗大晶粒,持续加工可能引发失效。结论经本构方程优化的拓展热加工图可较准确地指导ATM3303合金的热加工,数值计算结合实验是构建高精度低成本热加工图的新方法。

The work aims to investigate a low-cost method of obtaining a high-precision processing map with limited experimental data focusing on Mg-3Al-3Sn-0.3Mn(ATM3303)alloy.Based on the true strain-stress curves acquired from a few basic hot compression experiments,strain-compensated Arrhenius constitutive equations of ATM3303 alloy were figured out piecewise,which could predict more rheological stress of ATM3303 alloy in a wider processing range.The extended processing map of ATM3303 alloy was constructed with a combination of derived data and experimental data.The extended processing map was compared with the normal processing map constructed by only experimental data,and validation experiments were applied to reveal the precision of the two maps.Compared with the normal processing map,the instability area was smaller in the extended processing map optimized by constitutive equations.An unstable region in the normal processing map was predicted as a safe domain in the extended processing map.Hot compression experiments confirmed that the region was suitable for the hot processing of ATM3303 alloy.Furthermore,the extended processing map predicted an extra unstable region away from basic experimental conditions.Validation experiments showed that coarse grains were formed in ATM3303 alloy when processed under these conditions,and continuous processing might lead to material failure.In conclusion,the extended processing map optimized by constitutive equations can guide the hot processing of ATM3303 alloy more accurately,and it provides a new method for constructing high-precision and low-cost processing maps by the combination of numerical calculation and experiments.