介观尺度上热变形奥氏体储存能演化的计算机模拟

为了定量描述热变形奥氏体在介观尺度上微观变形的非均匀性，采用晶体塑性有限元方法(crystal plasticity finite element method，CPFEM)模拟了C—Mn钢在不同变形条件下的变形行为，得到了在介观尺度上奥氏体的微观应力应变和变形储存能分布．模拟所得到的应力一应变曲线与文献测定的应力一应变曲线基本一致．通过对真应变为0．5，变形速率为50s^-1的热变形奥氏体的研究发现，即使在外部的均匀变形条件下，无论是在晶粒内部还是晶粒间，材料内部变形都非常不均匀．这种变形不均匀性主要是由晶粒的初始取向不同，近邻晶粒的取向差，以及变形时滑移系的运动特性不同所引起的．本文定量描述了介观尺度上奥氏体变形储存能不均匀分布，为结合介观尺度组织模拟，实现组织演变的多尺度耦合计算提供了参考．

SIMULATION OF STORED ENERGY EVOLUTION IN HOT DEFORMED AUSTENITE ON A MESOSCALE

The distributions of the stress, strain and stored energy in hot deformed austenite were simulated by crystal plasticity finite element method (CPFEM) to evaluate quantitatively the deformation behavior on a mesoscale. The simulated stress-strain curves agree well with the experimental results measured in published literature. The simulation result revealed that the deformation behavior in the polycrystalline aggregates is inhomogeneous even if the exterior deformation conditions are homogeneous. This can be attributed to the different initial grain orientations, the different mis-orientation of neighboring grains and the different active slip systems. The simulations provide a means to obtain quantitative information on inhomogeneous distributions of stored energy in the austenite. Coupling CPFEM of the mesoscale simulation of solid phase transformation, the multiscale simulation of materials will be realized.