Effect of Inclusion on Step-wise S-N Characteristics in High Strength Steel

Abstract

In order to study the effect of inclusion on the step-wise S-N characteristics of high strength steel, cantilever-type rotary bending fatigue tests were performed at room temperature on two kinds of high carbon chromium steels with different cleanliness. It was found that the transition stress, transferring the fatigue fracture initiation from the specimen surface to the subsurface, did not depend on the cleanliness, but on the size of inclusions. In subsurface fracture region, fatigue life became shorter in steel with smaller inclusions, but the features of fish-eyes were almost the same.