열처리한 SM45C의 충격 및 조직적 특성

The Properties of Impact and Microstructure of Heat Treated SM45C

In this study, it has tested hardness, Charpy impact, microstructure and SEM fractography analysis after annealing, normalizing, quenching and tempering using impact specimens of SM45C. Hardness of tempering specimen after quenching was decreased according to increasing of tempering temperature, but impact values were increased. The structures of tempering below 400℃ showed bainitic tempered martensite, that of 400∼500℃ tempering appeared troostite, sorbite in 500∼650℃ tempering. The fractograph of quenched impact specimen was granular cleavage facet, and 100∼200℃ tempering fractographs were appeared some fibrous in cleavage facet. Tempering fractographs of above 400℃ have increased dimple of ductile.