选区激光熔化Inconel 625镍基合金Modified Johnson-Cook模型建立及流动应力预测

Modified Johnson-Cook Model Establishment and Flow Stress Prediction of Inconel 625Nickel-Based Alloy Melted by Selective Laser

以选区激光熔化技术制备Inconel 625合金试件,采用Gleeble 3800热模拟实验机对Inconel 625合金试件在700、800、900、1000℃,应变率1、0.1、0.01、0.001 s^(-1)条件下进行等温热压缩实验,研究增材制造该合金的高温流变行为,获得真实应力-应变曲线。分别采用Johnson-Cook模型及Modified Johnson-Cook模型建立了SLM Inconel 625合金本构模型,对比2个模型的预测精度。结果表明,原始Johnson-Cook模型误差AARE为83.53%,相关系数为0.77,误差极大;Modified Johnson-Cook模型误差AARE为14.87%,相关系数为0.98,Modified Johnson-Cook模型精度明显高于原始模型,具有较高的预测精度,能较好地反映增材制造Inconel 625合金的高温流变行为。最后分析压缩后试件微观金相组织,试件表现出硬化、再结晶软化现象,温度及应变率对材料微观组织影响明显。

In this paper,the selective laser melting(SLM)technology was used to prepare Inconel 625alloy specimens.Gleeble 3800thermal simulation experimental machine was used to produce Inconel 625alloy specimens at 700,800,900and 1000℃.The rheological behavior of the alloy at high temperature was studied by isothermal compression experiments at strain rates of 1,0.1,0.01,0.001s^(-1),and the real stress-strain curve was obtained.The constitutive model of SLM Inconel 625alloy was established by Johnson-Cook model and Modified Johnson-Cook model respectively,and the prediction accuracy of the two models was compared.The results show that the error of the original Johnson-Cook model is AARE 83.53%and the correlation coefficient is 0.77.The error AARE of the Modified Johnson-Cook model is 14.87%,and the correlation coefficient is 0.98.The accuracy of the Modified Johnson-Cook model is significantly higher than that of the original model,and it has higher prediction accuracy.The high temperature rheological behavior of Inconel 625alloy can be well reacted by additive manufacturing.Finally,microstructural analysis of compressed specimens reveals hardening and recrystallization softening,with temperature and strain rate significantly influencing material microstructure.