含稀土汽车用耐热镁合金的热变形行为  

Hot Deformation Behavior of Heat Resistant Magnesium Alloy Containing Rare Earth for Automobile

作　　者：郭正华 李志强 GUO Zheng-hua;LI Zhi-qiang(School of Automotive Engineering,Jiyuan Vocational and Technical College,Henan Jiyuan 459000,China)

机构地区：[1]济源职业技术学院汽车工程学院,河南济源459000

出　　处：《精密成形工程》2023年第4期91-98,共8页Journal of Netshape Forming Engineering

基　　金：河南省科技攻关项目(192102310244)。

摘　　要：目的为了开发出汽车用低成本、高性能Mg−Sm系耐热镁合金,需要考察镁合金热变形过程中变形温度、应变速率等对镁合金流变行为的影响,并建立流变应力本构方程,从而为实际工业生产中的加工工艺提供理论依据。方法采用Gleeble−3800型热力模拟试验机在变形温度350~450℃、应变速率0.001~1 s^(-1)的条件下对Mg−3.8Sm−1.2Zn−0.5Zr镁合金进行等温压缩变形,建立Mg−3.8Sm−1.2Zn−0.5Zr镁合金的流变应力本构方程,并对本构方程模型进行应变补偿。结果均匀化态Mg−3.8Sm−1.2Zn−0.5Zr镁合金中可见20~40µm的等轴晶晶粒和未回溶的第二相,主要物相为α−Mg和(Mg,Zn)3Sm相。Mg−3.8Sm−1.2Zn−0.5Zr镁合金的热变形激活能Q=238.95 kJ/mol,应力水平参数α=0.0140,结构因子A=3.6628×10^(16)。建立了Mg−3.8Sm−1.2Zn−0.5Zr镁合金的双曲正弦Arrhenius流变应力本构方程,并用温度补偿变形速率因子参数Z表达了Mg−3.8Sm−1.2Zn−0.5Zr镁合金流变应力本构方程。等温压缩热变形过程中,基于应变补偿的流变应力本构方程模型的相关系数为0.9939,绝对平均误差为6.898%,均方根误差为5.813,计算结果和试验值吻合较好。结论基于应变补偿的流变应力本构方程模型可以较为准确地对Mg−3.8Sm−1.2Zn−0.5Zr镁合金的流变应力进行预测。In order to develop Mg-Sm series heat-resistant magnesium alloys with low cost and high performance for automobiles,The work aims to investigate the influence of deformation temperature and strain rate on the rheological behavior of magnesium alloys during hot deformation,establish the constitutive equation of flow stress,and provide a theoretical basis for processing technology in actual industrial production.The isothermal compression deformation of Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloy at deformation temperature of 350-450℃and strain rate of 0.001-1 s^(–1)was carried out by Gleeble-3800 thermal simulation testing machine,the rheological stress constitutive equation of Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloy was established,and the strain compensation was carried out for the constitutive equation model.The results show that in the homogenized Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloy,there were 20-40µm equiaxed grains and undissolved second phase,the main phase wasα-Mg and(Mg,Zn)3Sm phases;hot deformation activation energy of Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloy Q=238.95 kJ/mol,stress level parameterα=0.0140,structure factor A=3.6628×10^(16),the hyperbolic sine Arrhenius flow stress constitutive equation of Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloy and the flow stress constitutive equation of Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloy expressed by the temperature compensated deformation rate factor Z were established;during isothermal compression hot deformation,the correlation coefficient is 0.9939,the absolute average error is 6.898%,and the root mean square error is 5.813 of the strain compensated rheological stress constitutive equation model,the calculated results were in good agreement with the experimental values.The strain compensated rheological stress constitutive equation model can accurately predict the rheological stress of Mg-3.8Sm-1.2Zn-0.5Zr magnesium alloys.

关 键 词：Mg−3.8Sm−1.2Zn−0.5Zr镁合金 变形温度 变形速率 本构方程 应变补偿 

分 类 号：TG146.22[一般工业技术—材料科学与工程]