高强7A62铝合金动态力学响应及其J-C本构关系

利用万能试验机和Hopkinson拉杆(SHTB)对7A62铝合金进行了准静态和动态拉伸性能测试,研究该合金室温及高温塑性流动应力动态响应特征,结合OM、SEM、TEM、DSC、LFA等测试对该合金的物理性能及原始微观组织进行分析。结果表明:7A62铝合金在大量高密度细小沉淀析出物粒子及亚微米级高熔点平衡析出粒子复合强化作用下,准静态屈服强度可达608 MPa。在室温动态变形过程中,该合金应变率强化效应显著。随着应变率高于684 s^-1时,合金屈服强度对应变率敏感性显著增强。在1100 s^-1、25~500℃条件下,合金表现出温度敏感性的沉淀强化相回溶及动态再结晶的热软化效应,500℃高温动态屈服强度超过200 MPa。在动态力学性能变化规律的基础上,建立了7A62铝合金的Johnson-Cook(J-C)本构模型。

Dynamic mechanical response and J-C constitutive equation of high strength 7A62 aluminum alloy

In order to study the dynamic response of plastic flow stress of 7A62 aluminum alloy at room temperature and high temperature,the quasi-static and dynamic tensile mechanical properties of 7A62 aluminum alloy were investigated by using universal testing machine and a Split Hopkinson Tensile Bar(SHTB).The physical properties and initial microstructure of the alloy were analyzed by OM,SEM,TEM,DSC and LFA.The results show that the quasi-static yield strength of 7A62 aluminum alloy can reach 608 MPa under the combined strengthening of numerous fine precipitates with high density and sub-micron high melting point equilibrium particles.The strain rate strengthening effect of the alloy is remarkable during dynamic deformation at room temperature.When the strain rate is higher than 684 s^-1,the yield strength of the alloy is larger sensitive to the strain rate.At strain rate of 1100 s^-1 and temperature of 25?500℃,the alloy shows some sensitivity to temperature due to thermal softening effect of the re-solution of strengthening precipitates and the dynamic recrystallization.And the dynamic yield strength exceeds 200 MPa at 500℃.The Johnson-Cook(J-C)constitutive model of 7A62 aluminum alloy was established based on the dynamic mechanical properties.