Multiscale Model of Transformation Induced Plasticity and its Application to Morphogenesis with High Functional

点击翻译按钮获取中文摘要

Transformation induced plasticity (TRIP) models have been developed on the basis of probability of cross slip in the austenite matrix, which is dominated by the thermal fluctuation and accounting for the crystalline structure of both phases. The transformation models were introduced to crystalline plasticity theory to develop a constitutive equation account for the transformation in crystalline scale. The validity of the proposed constitutive equations has been verified through the reproducibility of the transformation dependent on the strain rate, temperature, stress, carbon content and crystalline structure. It is also revealed that the formability of the TRIP steel can be substantially improved without remarkable loss of stiffness by controlling the deformation process precisely. Then the constitutive equations are encoded in the finite element / finite element homogenization methods to establish a new simulation method for a finding of a forming process which saves energy effectively. The method is not applied to real forming process but to simple cases ; however, it suggests that a suitable control of temperature improves the formability without substantial loss of stiffness, and that the forming limit is able to improve when the microstructure of TRIP steels is artificially introduced and controlled. Furthermore, a microscopic model based on the molecular dynamic method and lattice instability concept has been developed for the evaluation of molecular scale transformation.