Fatigue Limit Prediction of SUS630 Stainless Steel Matrix Based on Small Crack Mechanics
The experimentally obtained fatigue limit of high strength steel is generally a value reduced by inherent flaws, which does not characterize the resistance of high strength steel matrix to cyclic loading. To investigate the fatigue limit of matrix, fatigue tests of SUS630 stainless steel were performed. SUS630 stainless steel showed a distinct dual-stage S-N curve: one stage corresponding to high stress where crack initiated at the surface and another stage corresponding to low stress where crack initiated from the subsurface inclusion (Al2O3). Based on small crack mechanics, a model was proposed to predict the fatigue limit of SUS630 stainless steel matrix. Moreover, fatigue tests of blunt notch specimens were performed to examine the validity of this model.