Unified Plasticity Theory of Transformation plastic Behavior and the Microscopic Investigation

相变塑性（transformationplasticity，TP）对精确模拟金属热-力过程有着重要的作用，因此有必要对TP的机理和本构关系进行探讨。从连续介质力学的观点讨论了相变塑性的机理，并从热-力-相变塑性统一本构方程推导了相变塑性定律。本课题还在简单讨论相变过程中塑性变形发生在低于屈服应力的应力下的基础上，对由热力学和相变塑性统一理论导出的本构方程中出现的TP系数进行了识别。介绍了利用多功能试验机对几种钢的TP系数进行识别的结果，并将其作为材料数据之一，与其它数据一起应用于COSMAP程序对淬火过程的模拟。将模拟得到的温度、相位和应力/变形分布与实验测量值进行了比较，验证了计算的准确性。

The transformation plasticity (TP) is known to affect drastic contribution to accurate simulation of metallo-thermo-mechanical processes, which indicates the necessity of discussion on the mechanism and proper constitutive law of the TP. Mechanism of transformation plasticity (TP) is discussed from continuum mechanics viewpoint, and derivation of TP law from the unified thermo-mechanical and transformation plasticity constitutive equation. This project also motivates the identification of TP coefficient appearing in the constitutive equation derived from unified thermo-mechanical and transformation plasticity theory based on the simple discussion why the plastic deformation takes place under lower applied stress than yield stress during phase transformation. Result of identified TP coefficient for some steels by use of multi-functional testing machine is introduced as one of the material data together with other data to the simulation of a quenching process by use of newly developed code COSMAP. The simulated distribution of temperature, phases and stress/distortion are compared with the experimentally measured values to verify the accuracy.