GH4169高温合金的动态力学行为及其本构关系

采用材料试验机对GH4169高温合金光滑试样与缺口试样进行应变速率为0.000 1～0.010 0s-1下的室温准静态拉伸试验,再利用分离式霍普金森拉、压杆装置进行温度为20～400℃、应变速率为1×102～4×103 s-1下的动态拉伸、压缩试验,得到准静态和动态下的真应力-真应变曲线与失效应变;根据试验数据,采用分步拟合法确定了Johnson-Cook材料模型和失效模型参数,基于Johnson-Cook模型对动态压缩行为进行模拟,并进行试验验证。结果表明:GH4169高温合金的屈服强度随应变速率的增大而增大,随试验温度的升高而降低,该合金具有应变速率强化效应和温度软化效应;模拟结果与试验结果吻合得较好,真应力-真应变曲线的最大相对误差为5.91%,表明经修正后的Johnson-Cook模型可较好地描述GH4169高温合金的动态力学行为。

Dynamic Mechanical Behavior and Constitutive Relationship of Superalloy GH4169

The quasi-static tensile tests were conducted on smooth sample and notched sample of superalloy GH4169 under strain rates of 0.000 1-0.010 0s^-1 at room temperature by the material testing machine.The dynamic tensile and compression tests were conducted under strain rates of 1×10^2-4×10^3 s^-1 at 20-400 ℃ by split Hopkinson tension and pressure bar setup.The quasi-static and dynamic true stress-true strain curves and failure strains were obtained.Based on the experimental data,the parameters of Johnson-Cook material model and failure model were confirmed by the stepwise fitting method.The dynamic compression behavior was simulated by Johnson-Cook model,and verified by the experiment.The results show that the yield strength of superalloy GH4169 increased with the increase of strain rate,and decreased with the increase of test temperature;the alloy had a strain rate strengthening effect and a temperature softening effect.The simulation results were in good agreement with the experimental results,and the maximum relative error of the true stress-strain curve was 5.91%,indicating that the Johnson-Cook constitutive model could describe the dynamic mechanical behavior of superalloy GH4169 well.