日本刀の残留応力分布に及ぼす焼入れ条件の影響に関する数値シミュレーション

抄録

The Japanese sword uses the unique quenching method. The swordsmith pasts the clay as called "YAKIBATSUTI" on the surface of sword to control the heat transfer coefficient. Therefore, the cooling speed can be controlled at the hasaki and the other part. Then, the edge part transforms to the martensitic structure. The residual stress also changes from the phase transformation. In this study, the effect of the quenching condition on the residual stress distribution for the Japanese sword was investigated by the numerical simulation. Therefore, the setting area of heat transfer coefficient at the edge part was changed. First, the setting area of the high heat transfer coefficient was expanded. As the result, the residual stress at the center part was changed close to tensile stress from high compressive stress in the cross section. Second, focusing on the cooling temperature, the rapid cooling area was expanded because of change the area of heat transfer coefficient. Therefore, the martensitic area was also expanded. To summarize these results, the martensitic ratio was expanded by the changing the area of heat transfer coefficient. Residual stress was changed close to tensile stress from high compressive stress, because of expanding the martensitic area at the edge part.