Generalization of unified transformation-plasticity constitutive equation with identified material parameters and the application to metallo-thermo-mechanical simulation.

点击翻译按钮获取中文摘要

The project motivates to propose a model of evaluating the transformation plasticity, TP, coefficient by numerical calculation since identification of the coefficient so far needs complicated and time consuming experiments. A parallely connected two bar model consisted of mother and new phases is proposed : Tensile stress occurs in mother phase with larger thermal expansion coefficient in the course of cooling phase transformation, while compressive stress takes place in new phase with smaller coefficient in new phase. A tensile external stress even lower than yield stress is accelerated by the initial tensile stress in mother phase easily reaches yielding followed by plastic deformation. Simple thermo-elastic-plastic theory is employed to numerically calculate the rate and the current value of stress and strain in both phases depending on the amount of externally applied stress by use of material parameters for stress-strain relation and phase transformation kinetics characterized to material focused. Deviation of induced strain subjected to external stress from that of zero stress is now regarded as TP strain, and the TP coefficient is obtained by the TP strain divided by the external stress.