| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress the generation of inclusion starting flaking under severer use environment while allowing the existence of inclusions in a steel material to some extent.SOLUTION: In the roller bearing, at least one of an inner ring, an outer ring and a rolling is made of a steel material having a specified composition. The square root of the area of the maximum oxide based inclusion existing in an area of 30000 mmis 35μm or less when estimated by an extremum statistical process. A sulfide based inclusion having a minor axis of 4μm or more and existing in 320 mmof an area to be detected has the maximum aspect ratio of 6.5 or less, and the composition of the sulfide based inclusion is (MnS+CaS+MgS) or (MnS+CaS) including CaS of 5 mass% or more. A hardness Hv after quenching and tempering is 697-800.</p> |
