新型Al-Mg-Si-Cu合金的热变形行为及力学性能

Hot deformation and mechanical properties of novel Al-Mg-Si-Cu alloy

采用热模拟研究一种新型Al-Mg-Si-Cu合金的热变形行为,制定该合金的低温快速挤压工艺和在线热处理制度,利用电子万能实验机、光学显微镜、扫描电镜对合金的力学性能和组织进行分析。结果表明:新型Al-Mg-Si-Cu合金为正应变速率敏感材料;该合金的热压缩变形流变应力行为可用双曲正弦形式的本构方程来描述,也可用Zener-Hollomon参数来描述,其变形激活能为189.82kJ/mol;随着热变形温度的升高和应变速率的减小,合金的主要软化机制逐步由动态回复转变为动态再结晶;合金低温快速挤压后,经过在线风淬停留3h,然后200℃人工时效3h,其抗拉强度达到305MPa,屈服强度达到265MPa。

The hot deformation of a novel Al-Mg-Si-Cu alloy was studied by thermal simulation.High-speed extrusion process at low temperature and on-line heat treatment were developed.Mechanical properties and microstructures were analyzed by universal testing machine,optical microscopy and scanning electron microscopy.The results show that the novel Al-Mg-Si-Cu alloy is sensitive to strain rate.The hot deformation behavior of this alloy can be described by a constitutive equation in hyperbolic sine function,and can also be described by a Zener-Hollomon parameter with a hot deformation activation energy of 189.82 kJ/mol.The softening mechanism transforms from dynamic recovery to dynamic recrystallization with increasing temperature and decreasing strain rate.After high-speed extrusion at low temperatures,on-line air quenching for 3 h,and artificial aging at 200℃ for 3 h,the tensile strength of the alloy reaches 305 MPa,with the yield strength of 265 MPa.