The fatigue behaviour of metastable (AISI-304) austenitic stainless steel wires

The fatigue behaviour of AISI 304 stainless steel has been investigated as a function of drawing strain. Both smooth and notched wire samples were subjected to three-point fatigue testing carried out under load control at room temperature. This study has established that approximately 20% of prior deformation-induced martensite is a critical amount which determines the subsequent fatigue response of this steel. In steel with less than 20% of deformation-induced martensite, any martensite formed during the fatigue process will act beneficially by retarding fatigue cracking, raising the fatigue limit and resulting in a ductile fatigue fracture. However, in the presence of more than 20% of deformation-induced martensite, any martensite induced by cyclic strain will encourage more rapid crack initiation which leads to more brittle fracture surface characteristics. A scenario for predicting the fatigue behaviour of cold drawn AISI 304 stainless steel wire has been proposed in this study.