中文摘要：

根据高温流动应力行为的主导软化机制不同,建立了低碳钢热塑性成形过程的动态回复和动态再结晶两阶段本构模型.采用单一内变量的位错密度演化模型描述加工硬化和动态回复对流动应力的影响;应用Avrami方程表达动态再结晶软化作用对流动应力的影响.采用Gleeble1500热模拟实验机对低碳钢进行热压缩实验,依据实验流动应力曲线确定本构模型中的参数,并分析了模型参数随变形条件的变化规律.应用建立的本构模型计算实验条件下的流变曲线,结果计算值与实验值吻合良好,表明所建立的本构模型可以用于低碳钢热压缩成形过程的数值模拟.

英文摘要：

Based on the analysis of hot deformation behavior,a two-stage constitutive model of low carbon steel was developed.In the model,the effect of work hardening and dynamic recovery on the flow stress is described by a one-structure parameter model（dislocation evolution model）;the softening effect of dynamic recrystallization is expressed by the Avrami equation.The model parameters are identified by using the experimental stress-strain curves obtained from the hot compressive deformation on Gleeble-1500 thermo-simulation machine,and then the variation of model parameters with deformation condition are investigated.The calculated flow stress curves agree well with the measured ones,which indicates that the developed constitutive model is applicable to the hot deformation process numerical simulation of the investigated low carbon steel.