抄録
Cantilever type rotational bending fatigue tests were carried out in super-long fatigue life range for high carbon chromium bearing steel. The fatigue properties and the fatigue crack initiation were investigated. The stress intensity factor calculated from the area of rough surface region of "Facet" in the fish-eye was independent on the stress amplitude and was almost a constant. This fact suggests that when the stress intensity factor reached to a constant of 5.4 MPam^<1/2>, the fatigue crack propagate depend on the stress amplitude. On the other hand, it is found by SEM observation, that the fracture in the mode of "Inclusion on Subsurface", is caused by a dark region near the specimen surface. There is a small inclusions caused by segregation on subsurface in this dark region. The crack initiates outside of the dark region, same as the mode of the mode of " Fish-eye" that the crack initiates in the region of "Flat".
