MARTENSITE FORMATION AND THE RELATED TOUGHNESS IN 304 STAINLESS STEEL DURING LOW TEMPERATURE FATIGUE

Abstract

Abstract— Effect of transformed martensite during low temperature fatigue in metastable 304 stainless steel on low temperature toughness were investigated. Low temperature fatigue was mainly conducted at R = 0.1 with maximum stress of 1030 MPa at −196°C. The amount of martensite during fatigue cyclic deformation was related to the reduction of impact toughness and to the apparent fracture toughness. Beyond 30% of martensite formation, a strong decrease of low temperature impact toughness was found. This phenomenon is related to the phase stability of the metastable austenitic phase.