基于变形机制的P91钢蠕变行为分析

DEFORMATION-MECHANISM-BASED MODELING OF CREEP BEHAVIOR OF P91 STEEL

利用一种基于变形机制的本构模型对P91钢蠕变行为进行了研究。结合试验数据发现,最小蠕变速率与蠕变过程中的施加应力呈现出明显的指数关系,且与不同的变形机制间存在紧密联系。通过将位错滑移、位错攀移以及晶界滑移三种变形机制引入传统Norton幂律方程,对P91钢在580℃~620℃温度、135 MPa~200 MPa应力条件下的蠕变行为进行模拟分析。结果表明,利用该模型可以较好地描述P91钢的蠕变曲线,包括蠕变的初始阶段、稳态阶段以及加速阶段。此外,模型计算结果及扫描电镜观察分析进一步表明,在当前温度应力范围内P91钢蠕变断裂形式为穿晶断裂。

Creep behavior of P91 steel was studied by using a constitutive model based on deformation mechanism.Combined with the experimental data,it was found that the minimum creep rate has an obvious exponential relationship with the applied stress during creep,which was closely related to different deformation mechanisms.By introducing dislocation slip,dislocation climb and grain boundary slip into the traditional Norton power law equation,the creep behavior of P91 steel under the conditions of 580℃~620℃and 135 MPa~200 MPa stress was simulated and analyzed.The results show that the creep curve of P91 steel can be well described by using this model,including the initial stage,steady stage and acceleration stage of creep.In addition,the results of model calculation and SEM analysis further show that the creep fracture form of P91 steel is transgranular fracture within the current temperature stress range.