【作者】 唐宁；

【导师】 闫牧夫；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2008， 硕士

【摘要】 本文在综合分析现有相场模型的基础上,研究了多晶体塑性变形和动态再结晶过程中的组织形貌演变规律。基于金兹堡-朗道(Ginzburg-Landau)相变理论,以形变动态再结晶机制理论为依据,并考虑双势阱函数和场变量之间存在交互作用,用变异常数法构建了表征形变储能与动态再结晶形核长大的自由能泛函表达式,并给出了求解该方程的数值方法。结合热力学与动力学理论,建立了热挤压变形模拟过程中相场唯象参数与变形温度、变形量和应变速率的半经验定量表达式。在此关系和再结晶相场自由能方程的基础上建立了适用于Aermet100钢热挤压变形动态再结晶的相场模型。基于该模型,用面向对象的程序开发工具编制了相场模拟软件,实现了宏观参数输入和微观结果输出、存储、显示、统计的自动运行,为Aermet100钢动态再结晶过程的多尺度间接同步耦合模拟创造了条件。对热挤压变形过程中工件上不同点的晶粒演变进行了模拟预报。模拟结果表明,塑性变形引起的晶界拉长和扭折是促进再结晶形核的主要因素。在变形过程中,工件平均晶粒尺寸随着再结晶体积分数的增加急剧减小,在再结晶完成后又有缓慢增加。模拟结果与试验结果基本吻合。在此基础上,进行了实际件模锻过程晶粒演变的相场模拟预报。更多还原

【Abstract】 This paper deals with plastic deformation and dynamic recrystallization of polycrystal material based on the resultant analysis of present phase field models. The phase-field models to describe plastic deformation and dynamic recrystallization have been deduced on basis of Ginzburg-Landau (G-L) theory and dynamic recrystallization theory by means of coefficient variation considering double well potential and interaction of orientation field variable. The numerical method to solve the models mentioned above is also given.The dependency of phenomenological phase field parameter of temperature, strain and strain rate during hot extruding is measured with semiempirical method resultantly considering related thermodynamic and kinetic theory. Phase field model appropriate for dynamic recrystallization during hot extrude of steel Aermet100 is established on basis of recrystallization phase field free energy equation and the dependency mentioned above.According to this model, software for phase field simulation is designed and compiled with object oriented programming system, which input the macroscopic data and output,store,display and analysis the caculated result.multi-scaled indirect synchro coupling simulation of recrystallization of steel Aermet100 is based on this software.Numerical simulation and forecast of grain evolution during hot extruding is applied on different position of work piece. the caculated result indicates that the grain boundery has been elongated and kinked consequently during plastic deformaton,which mainly caused nucleation of recrystallization. it also shows that the average grain size decreases rapidly with the increase of the fraction of recrystallized grain and increases gradually after complete recrystallization. The predicted results agree basically with the experimental ones. grain evolution during hot die forging of actual part is also forecasted with the above phase field model.更多还原