Unified Plasticity Theory of Transformation plastic Behavior and the Microscopic Investigation

相变塑性(TP)对金属热机械过程的精确模拟有很大的贡献，这表明有必要对TP的机制和适当的本构关系进行讨论。从连续介质力学的角度讨论了相变塑性的机理，并从统一的热力学本构方程和相变塑性本构方程出发推导了相变塑性定律。在简单讨论相变过程中塑性变形在低于屈服应力的情况下发生塑性变形的基础上，从热力学和相变塑性统一理论出发，对本构方程中出现的Tp系数进行了识别。介绍了用多功能试验机测定某些钢的TP系数的结果，并与其他数据一起作为材料数据，利用新开发的COSMAP程序对淬火过程进行了模拟。将模拟得到的温度分布、相分布和应力/变形分布与实测值进行了比较，验证了模拟的准确性。

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.