| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive and long-lived bearing in the environment in which water and solid foreign matter get mixed in lubricant as in a bearing for a rolling mill. SOLUTION: Carbon concentration of at least one rolling surface of an inner ring, outer ring, and a rolling unit is set to 0.30% or more 0.80% or less, so as to hold hardness of required minimum limit and reduce deposition of film- state carbide in an old austenite grain boundary of the rolling surface. An amount of P, Sb, As promoting deposition of this film-state carbide is specified. An amount of Al, N, Mo, B, Nb, V having an effect fine dispersing the carbide is specified. An existence frequency of oxide system inclusion of 13μm or more harmful for a corrosive fatigue life is specified, and an amount of O and S of element thereof is specified. A hermetic seal is mounted for suppressing infiltration of solid foreign matter, a roller of 20 mm or more is used for the rolling unit. For maintaining surface hardness of the rolling surface, a residual austenite amount is specified.
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