Pesearch Paper / Mechanical Behaviors : Development of a Fatigue Life Lextension Method by Dispersing Micro - sized Martensite Particles in Austenitic Stainless Steel - ( 2 ) - Microstructure Evolution -
명태호Tai Ho Myeong,비후시길Yakichi Higo
Abstract
High cycle fatigue tests were performed on both as-received material (SUS 304: an austenitic stainless steel) and the material with dispersed micro-sized α martensite particles by cooling at -78℃. In a high cycle regime, the fatigue life of the material with dispersed micro-sized α martensite particles was much longer than that of the as-received material. After high cycle fatigue test, dislocation structure and micro-structure (longitudinal section) observations were carried out using a TEM and a laser microscope, respectively. It was found that the re-arrangement of dislocations and the formation of large α martensite, which may cause fatigue crack initiation were suppressed in the material with dispersed micro-sized α martensite particles as compared to the as-received material.