7050铝合金流变模型及稳态热加工工艺研究

Study on rheological model and steady hot working process of 7050 aluminum alloy

为研究7050铝合金的高温流变行为和热加工工艺窗口,在变形温度为573~723 K、应变速率为0.01~10 s^(-1)的条件下对其进行等温压缩实验,获得了16组流变数据,基于该流变数据,提出了新本构模型并与经典模型在预测精度、材料参数及求解算法方面进行了对比分析。结果表明:新模型的预测精度最高、HS模型的预测精度最低;新模型和HS模型的材料参数获取仅需要多元线性回归,而AH模型需要使用多元非线性回归;新模型有30个参数、AH模型有24个参数、HS模型有9个参数,新模型在未显著增加材料参数的前提下降低了参数获取难度并显著提升了预测精度。此外,基于新模型推导出7050铝合金热加工图的解析方程并绘制了热加工图,并通过微观组织分析验证了热加工图的有效性。结果表明:变形温度在623~723 K、应变速率在0.01~10 s^(-1)范围内发生失稳的风险较小,能量耗散率大约在20%~40%范围内,材料能够充分发生动态再结晶。

In order to investigate the high-temperature rheological behavior and thermal working process window of 7050 aluminum alloy,the isothermal compression experiments were conducted under the conditions of the deformation temperature of 573-723 K and the strain rate of 0.01-10 s^(-1),and sixteen sets of rheological data were obtained.Then,based on these rheological data,a new constitutive model was proposed and compared with classical models in terms of prediction accuracy,material parameters and solution algorithms.The results indicate that the new model has the highest prediction accuracy,while HS model has the lowest prediction accuracy.Material parameter ac-quisition obtaining of the new model and HS model only requires multiple linear regression,and AH model requires multiple nonlinear re-gression.The new model has therty parameters,AH model has twenty-four parameters,and HS model has nine parameters.It can be seen that the new model reduces the difficulty of parameter acquisition and significantly improves the prediction accuracy without significantly in-creasing the number of material parameters.In addition,based on the new model,the analytical equation of hot processing map for 7050 alu-minum alloy was deduced,and its hot processing map was drawn.The microstructure analysis results verify the effectiveness of the hot pro-cessing map.The results show the risk of instability is small at the deformation temperature of 623-723 K and the strain rate of 0.01-10 s^(-1).The energy dissipation rate is approximately in the range of 20%-40%,and the material can fully undergo the dynamic recrystallization.