Rolling bearing
AssigneeKoyo Seiko Co., Ltd.
InventorsToshiharu Watanabe, Hajime Tazumi
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Abstract
A structure of at least a stationary-side race of a bearing is transformed into a lower bainite structure through an isothermal transformation treatment. Furthermore, the adjustment is made for hardness to HRC=54 to 64, an amount of residual austenite to not more than 5% and an area percentage of 0.8 μm or longer carbide to not more than 20% based on the total area of secondary carbide. Thus is prevented the occurrence of a white layer in the rolling bearing.
Claims6
A rolling bearing comprising races and a rolling element each constructed from steel,
- wherein a structure of at least a stationary-side race is transformed into a lower bainite structure through isothermal transformation and is adjusted for hardness to HRC=54 to 64, an amount of residual austenite to not more than 5%, and an area percentage of 0.8 μm or longer carbide to not more than 20% based on a total area of secondary carbide.
A method for improving ball bearings to avoid the occurrence of premature flaking of ball bearing raceway surface comprising:
- subjecting said ball bearing to a sufficient temperature to carry out austenitizing and thereafter an isothermal transformation treatment, wherein said austenitizing is carried out at temperature of at least 840° C. for at least 40 minutes.
A method for improving ball bearings to avoid the occurrence of premature flaking of ball bearing raceway surface comprising:
- subjecting said ball bearing to a sufficient temperature to carry out austenitizing and thereafter an isothermal transformation treatment, wherein said isothermal transformation is carried out for at least 1 hour at 230° C.
A method for improving ball bearings to avoid the occurrence of premature flaking of ball bearing raceway surface comprising:
- subjecting said ball bearing to a sufficient temperature to carry out austenitizing and thereafter an isothermal transformation treatment, wherein the ball bearing is immersed into a salt bath for the isothermal transformation maintained at a transformation treatment temperature.
Dependencies are inferred from the claim text.