炭素鋼の微視的構造解析におけるFe-Fe₃C間の簡易モデル化の検討

抄録

Steel materials typified by carbon steel are one of the important materials of social infrastructure. When handling these materials in numerical simulation, they are generally modeled as homogeneous continuum. This is because microscopic structures having various orientations are randomly combined, and as macroscopically can be considered as an isotropic body as a result. On the other hand, each such microscopic structure has a complicated structure. The microscopic structure of steel, in particular the kinematic behavior of cementite, is closely related to the ductile fracture of steel materials. That is, cementite in the steel material cracks during loading, and the void formed in the cracked region spreads, eventually leading to ductile fracture. When considering this series of phenomena as the progress of damage inside the material, it is interesting to see how the damage progresses. In the concept of continuum damage mechanics, not only general variables used for description of deformation, but also new internal variables with unique relationship with internal damage process are introduced to express damage inside the material. Alternatively, using multi-scale analysis based on homogenization method, it is possible to reflect the mechanical response of the microscopic structure as the material property of the macroscopic structure. By using this method, we can express internal damage of the material without preparing new variables representing damage. In this research, we focus on the growth behavior of the voids in the microstructure of the carbon steel after voids are generated, and propose a simple model that characterizes the growth phenomenon. Then, using this model, we perform micro and macro structure coupled analysis based on homogenization method.