Grain refinement effect on fatigue properties of austenitic stainless steel with deformation induced martensite formation

Fatigue properties of metastable austenitic 301LN steel with coarse and ultrafine-grained microstructures were investigated at ambient temperature and the effect of grain refinement was evaluated. Two different microstructural states of material were introduced by different annealing conditions during special thermomechanical treatment. Fatigue life curves were obtained and compared for both coarse-grained and ultrafine- grained states of austenitic stainless steel. Magnetic measurements before, during and after cyclic loading were performed to reveal structural changes, i.e. formation of deformation-induced martensite. Relationship between microstructure refinement, phase composition and fatigue properties was discussed