Abstract
Mechanism of interior inclusion induced fracture of bearing steel in long life region was experimentally examined under rotating bending, and discussed from a viewpoint of electron microscope observation. Fish-eye was formed on the fracture surface in the interior inclusion induced fracture, and rough surface area was necessarily observed near the inclusion. Based on TEM observation of longitudinal section of fracture surface, it was found that structural changes were caused around the inclusion. Fine grains caused around the inclusion have the sizes within 40nm. It seems that the rough surface area around the inclusion is the boundary of this fine grain region and matrix.
