Fatigue behaviours of a martensitic compressor valve stainless steel with small amount of retained austenite

Impact and bending fatigue strengths are essential properties for compressor valve steels.The increase in efficiency of compressors requires higher performance valve steels.This paper describes the influence of retained austenite on the fatigue strengths in tension, bending and impact for a modified CrMo martensitic stainless compressor valve steel.It is shown that the impact fatigue strength was significantly improved with increasing retained austenite.The bending fatigue strength was also improved, but reached a maximum value at about 4vol% retained austenite.However, the presence of retained austenite had little influence on the fatigue strength in tension.These different fatigue behaviours were discussed in relation to the microstructures and were interpreted in terms of fracture mechanisms.