中文摘要：

针对耐热不锈钢X8CrNi25-21的材料特性,基于弹塑性力学理论和位错动力学对经典的Johnson-Cook（JC）本构模型进行修正,引入位错塞积理论,并在本构中考虑晶粒尺寸和晶体取向等微观参数,建立了基于尺度效应的耐热不锈钢X8CrNi25-21介观尺度材料响应行为本构模型.通过采用介观尺度非标准件,并利用热处理工艺改变材料的晶粒尺寸,开展准静态拉伸实验、动态霍普金森压杆实验进行介观尺度材料测试,建立了晶体尺寸与介观尺度材料塑性变形与断裂行为特征的变化规律,并最终确定了耐热不锈钢X8CrNi25-21介观尺度材料本构模型各参数值.

英文摘要：

Considering the characteristic of heat resistant stainless steel X8CrNi25-21,the classical constitutive model Johnson-Cook（JC）was modified based on plasticity-elasticity mechanics and dislocation dynamics.A constitutive model was established based on the dislocation theory,which could reflect the size effect and mesoscopic response behavior.Based on dislocation pile-up model,some experiments were conducted,including quasi-static tension and SHPB tests,to analyze microscopic parameters such as crystal size and crystal orientation.The objects used in the experiments were of mesoscale nonstandard parts,making corresponding heat treatment process to change sample grain size.The material experiment results show the performance change regularity of microscopic plastic distortion and parting action,and provide parameters for the mesoscopic constitutive model of heat resistant stainless steel X8CrNi25-21.