Unified Plasticity Theory of Transformation plastic Behavior and the Microscopic Investigation

相变塑性对金属热机械过程的精确模拟有重要的影响，这表明有必要对相变塑性的机理和合理的本构规律进行探讨。从连续介质力学的角度讨论了相变塑性的机理，并从统一的热-力学和相变塑性本构方程推导了相变塑性规律。在简单讨论相变过程中，为什么塑性变形发生在较低的外加应力下而不是屈服应力下的原因的基础上，本项目还推动了在统一的热-机械和相变塑性理论推导的本构方程中出现TP系数的识别。本文介绍了多功能试验机对某些钢的TP系数的识别结果，并将其作为材料数据之一，与其它数据一起应用新开发的COSMAP程序进行淬火过程的模拟。将模拟得到的温度分布、相分布和应力/变形分布与实验测量值进行了比较，以验证其准确性。

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.