非热弹性马氏体相变的细观本构模型

A micro-mechanical model of non-thermo-elastic martensitic transformation

为了更清楚地认识铁基合金经受非热弹性马氏体相变的本征特性,在细观尺度对非热弹性马氏体相变进行了研究.基于马氏体相变晶体学和内变量本构理论建立了非热弹性马氏体相变的细观本构模型.该模型采用微区相变应变、奥氏体及马氏体的塑性应变表征宏观的非弹性响应,把奥氏体和马氏体变体的等效塑性应变率和体积分数变化率作为内变量描述微观结构变化.模型采用J2流动理论描述微区塑性流动,与采用晶体塑性的描述方法相比模型更简单,且更适用于工程计算.单晶奥氏体单变体简单剪切的模拟结果表明:随着应变的增加,先发生奥氏体塑性变形,进而发生相变,马氏体体积分数与应变呈线性关系;温度较低时易发生马氏体相变并使得材料的强度提高.

In order to describe the intrinsic characteristic of ferrous alloy during martensitic transformation, micro-mechanical behavior of non-thermo-elastic martensitic transformation was investigated. Based on the crystallographic theory of martensitic transformation and internal variable constitutive theory, a micro-mechanical constitutive model of non-thermo-elastic martensitic transformation was developed. Plastic strains of product and parent phases as well as the volume fraction of each martensitic variant were taken as the internal variables describing the microstructure evolution of the micro-domain. The constitutive equation of an austenitic single crystal was presented. Only plasticity in the sense of J2 flow theory was considered at the level of micro-region because of high calculation efforts. The micro-mechanical model was applied to the behavior study under uniaxial loading. It is showed that non-thermo-elastic martensitic transformation occurs with the increasing strain, which enhances the intensity of the material.