炭素鋼のパルスYAGレーザ焼入れに及ぼす照射面の形状効果(第1報) : レーザ光軸と照射面が垂直の場合

概要

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Numerical simulation of pulsed YAG laser surface hardening process of a carbon steel with cylindrically rugged shape is implemented by use of the heat treatment simulation code "HEARTS" based on metallo-thermo-mechanics developed by one of the authors. In this first report, the coupled fields of metallic structure due to phase transformation, temperature and stress/distortion are evaluated in the case when laser optical axis is perpendicular to irradiation surface. The results are summarized as follows: Temperature distribution due to irradiated heat input and successive diffusion depends on the geometric shape of the specimen, so affecting the hardening characteristics of the material. Especially, irradiation to cylindrical specimen of convex type with small radius produces martensite in the entire region. No hardened shape effect is, however, found in the bodies with large enough dimension for thermal diffusion such as convex cylinder with large radius and concave cylinder as well as flat surface. It is also concluded that extremely high residual stresses are generated after the processing in small cylindrically rugged part.