Abstract
Two-step variable amplitude loading tests were conducted on a high carbon chromium steel, JIS SUJ2,in order to estimate subsurface crack initiation life. Particular emphasis was placed on the granular area seen around a non-metallic inclusion in fish-eye. It is known that the granular area does not appear in short life region at high stress levels, but appears in long life region at low stress levels. Therefore, making use of this property, low-high sequences with different cycle ratios at low stress level were applied to FPB-treated specimens. If the granular area is observed after testing, it can be concluded that the granular area was generated at a cycle ratio examined. It was found that subsurface crack initiation took place at an early stage of fatigue life, i.e. 5% or so.
