合金设计对贝氏体相变动力学影响的建模研究

采用基于形核控制机制的贝氏体等温相变动力学模型研究了合金设计对贝氏体相变动力学的影响.针对两种贝氏体高强钢，采用热膨胀仪在425~350℃开展了等温贝氏体相变实验，观察到了不同程度的贝氏体不完全相变现象.基于形核控制机制，采用切变型相变动力学模型对两种实验钢的贝氏体等温相变行为进行了建模研究，模型中同时考虑了晶界形核和自催化形核.最后，对比分析了两种实验钢中形核激活能、未转变奥氏体体积分数以及形核速率等的差异，为贝氏体高强钢的成分设计及工艺创新提供理论指导.

Modeling Research on Influence of Alloy Design on Bainite Transformation Kenitics

A kinetic model of bainite isothermal transformation based on nucleation-controlled mechanism was used to study the effect of alloy design on bainite transformation kinetics. Using two kinds of high-strength bainite steels， isothermal bainite transformation experiments were conducted at 425~350℃ with a dilatometer. Different degrees of incomplete phase transformation phenomenon are observed. Based on nucleation-controlled mechanism， the displacive transformation kenetic model was used to describe the bainite isothermal transformation behavior of two experimental steels， where grain-boundary nucleation and autocatalytic nucleation were both considered. Finally， the difference in activation energy of nucleation， volume fraction of untransformed austenite and the nucleation rate etc between two experimental steels were comparatively analyzed， which provide theoretical guidance for the composition design and process innovation of high-strength bainite steel.