Fatigue property and its probabilistic character of S06 steel

The fatigue property between 10⁴~10⁷ cycles of S06 steel, which is a new kind of precipitation-hardened stainless steel with high yield strength, was tested with PLG-100C high-cycle fatigue testing machine. With the decrease of stress amplitude, more fatigue crack initiated from subsurface. The fatigue life of specimens where fatigue crack initiates from subsurface is longer than that of specimens where fatigue crack initiates from surface at the same stress amplitude. To estimate the probabilistic character of fatigue property in high cycle range, the fatigue data of interior initiation was researched: maximum likelihood method and Kolmogorov test method considering life truncate data was used to research the distribution of fatigue life and result shows that fatigue life follows lognormal distribution in long life region; maximum likelihood method considering life truncate data was used to fit P-S-N curve; the P-S-N curve was used to discuss the distribution of fatigue strength in long life region.