Abstract
This paper presents the fatigue behavior of high strength steel, SCM435, under constant amplitude loading and repeated two step loading in ultra high-cycle region. The axial loading fatigue tests of R=-1 was conducted at frequency of 1〜200Hz. The area that was called the Fish-eye and FGA was observed in the fracture surface. In addition, beach marks were observed in Fish-eye under repeated two-step loadings. However, signs of the Two-step loading like the beach mark were not observed in FGA. In addition, it was forecast that a low stress and a high stress did not mutually influence the growth of FGA since it became a value close to one by using the Minor low.
