Rolling bearing
AssigneeNsk Ltd.
InventorsHideyuki HIDAKA, Daisuke WATANUKI, Kazuki TAMURA
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Abstract
A rolling bearing in which at least one of the bearing rings is obtained by applying a induction heat treatment to a spheroidizing annealed steel material having a DI value of 1.0 or more to form a hardened layer having a hardness of 550 HV or more on at least a raceway surface and a fitting surface. In the induction heat-treated bearing ring, (A) an average retained austenite amount is 12 vol % or less, (B) the raceway surface has a retained austenite amount of 12 vol % or more and a residual compressive stress of −100 MPa or less, and (C) a difference between a hardness of the raceway surface and a minimum hardness of a region having a hardness of less than 550 HV is 150 HV or more.
Claims10
A rolling bearing comprising one or more parts of a pair of bearing rings and a rolling element, wherein:
- at least one of the bearing rings is obtained by applying a induction heat treatment to a spheroidizing annealed steel material having a DI value represented by the following formula (1) of 1.0 or more to form a hardened layer having a hardness of 550 HV or more on at least a raceway surface and a fitting surface, and
- in the induction heat-treated bearing ring, the raceway surface has a retained austenite amount of 12 vol % or more, and a difference between a hardness of the raceway surface and a minimum hardness of a region having a hardness of less than 550 HV is 150 HV or more,
- DI=D0×fSi×fMn×fNi×fCr×fMo (1)
- D0=0.2×(C)+0.14
- fSi=1+0.64×(Si)
- fMn=1+4.1×(Mn)
- fNi=1+0.52×(Ni)
- fCr=1+2.33×(Cr)
- fMo=1+3.14×(Mo)
- where (C), (Si), (Mn), (Ni), (Cr) and (Mo) are contents (mass %) of respective elements in the steel material.
Dependencies are inferred from the claim text.