가공열처리한 316L 스테인리스강의 기계적 성질과 감쇠능

Abstract

This study was carried out to investigate the relationship between the mechanical properties and damping capacity of thermo-mechanical treated 316L stainless steel. Dislocations, ε and αʹ-martensites were formed by thermo-mechanical treatment, and the grain size was changed from micrometer to sub-micrometer by 5-cycled thermo-mechanical treatment. The volume fraction of dislocations, ε and αʹ-martensites was increased, and grain size of austenite increased and lengthened by the with increasing cycle number of thermo-mechanical treatment. In 5-cycled specimens, the volume fraction of αʹ-martensite was more than 25% and the less than 5% of volume fraction of ε-martensite was attained. With increasing number of thermo-mechanical treatment, hardness, strength and damping capacity were increased, but elongation was decreased. Damping capacity was increased with increased hardness and strength, but decreased with increased elongation, and this result was the opposite tendency for general metal.

This study was carried out to investigate the effect of thermo-mechanical treatment on the formation behavior of martensite in 316L stainless steel. Dislocation, αʹ and ε-martensite were formed by thermo-mechanical treatment. Martensite with surface relief and specific direction was formed by thermo-mechanical treatment. Martensite formed by thermo-mechanical treatment were reversed to austenite with an ultra-fine grain size of less than 1㎛ by annealing treatment at 700℃ for 20min. αʹ-martensite with a K-S orientation relationship and ε-martensite with a [110]‖[100]ε orientation relationship to the matrix was formed by thermo-mechanical treatment. The volume fraction of dislocation, αʹ and ε-martensite were increased with the cycle number of thermo-mechanical treatment. In 5-cycle number thermo-mechanical treated specimens, more than 25% of the volume fraction of αʹ-martensite and less than 5% of the volume fraction of ε-martensite were attained. The austenite grains were fairly deformed by thermo-mechanical treatment and the grain size of austenite with various orientation relationship were changed from micrometer to sub-micrometer by the 5-cycle thermo-mechanical treatment.