A Study on the Fatigue Failure Behavior SM45C on Ion-Nitrided under Alternating Tension-Compression Axial Loading

반복 인장-압축하중을 받는 이온질화처리한 SM 45C의 피로파괴거동에 관한 연구

  • Man, Chang-Gi (Dept.of Machanical Engineering, Graduate School of Dankook University) ;
  • Kim, Hui-Song (Dept.of Machanical Engineering, Dankook University)
  • 만창기 (단국대학교 대학원 기계공학과) ;
  • 김희송 (단국대학교 기계공학과)
  • Published : 1988.09.01

Abstract

This paper dealt with experimentally the effect of $N_2$ and $H_2$ gas mixtures ratio in the fatigue characteristics of SM45C on Ion-nitrided. The specimen were treated water cooling after Ion-nitriding at $500^{\circ}C$ and 5 torr. in 80% $N_2$and 50% $N_2$gas mixtures ratio in the atmosphere for 3 hrs. The hardness distribution and the depth of nitriding layer shows more increase in 80% $N_2$gas mixture ratio than 50% $N_2$. Ion-nitrided specim- en for 80% $N_2$gas mixture ratio show more increase infatigue strenght in the $>1.5{\times}10^5$ cycles region than 50% $N_2$. In the $<1.5{\times}10^5$cycles region, fatigue failure is due to cracking of the brittle nitrided case, and the propergation of the surface cracks into the core. But in the $>1.5{\times}10^5$cycles region, it is found that cracks propagate from the non-metallic inclusions in the subsurface.

Keywords