Bearing part, rolling bearing, and method for manufacturing bearing part
AssigneeNtn Corporation
InventorsMasahiro YAMADA, Chikara OHKI
Life of this patent
Estimating the term…
Abstract
A bearing part is composed of a chromium molybdenum steel, and includes a raceway surface or a rolling contact surface. A precipitated compound composed of at least one of a carbide, a nitride, and a carbonitride exist in the raceway surface or the rolling contact surface. An area ratio of the precipitated compound in the raceway surface or the rolling contact surface is more than or equal to 3%. An average grain size of the precipitated compound in the raceway surface or the rolling contact surface is less than or equal to 0.3 μm.
Claims14
A bearing part composed of a chromium molybdenum steel, the bearing part comprising a raceway surface or a rolling contact surface, wherein
- compound grains each composed of at least one of a carbide, a nitride, and a carbonitride exist in the raceway surface or the rolling contact surface,
- an area ratio of the compound grains in the raceway surface or the rolling contact surface is more than or equal to 3%, and
- an average grain size of the compound grains in the raceway surface or the rolling contact surface is less than or equal to 0.3 μm.
A method for manufacturing a bearing part, the method comprising:
- preparing a formed body composed of a chromium molybdenum steel;
- carbonitriding the formed body by heating the formed body to more than or equal to 930° C. and less than or equal to 940° C. in a carbonitriding atmosphere including ammonia;
- primarily quenching the carbonitrided formed body by heating the formed body to a primary quenching temperature of more than 850° C. and less than 930° C. and then cooling the formed body to a temperature of less than or equal to a Ms point;
- secondarily quenching the primarily quenched formed body by heating the formed body to a secondary quenching temperature of more than or equal to an A1 point and less than 850° C. and then cooling the formed body to the temperature of less than or equal to the Ms point.
Dependencies are inferred from the claim text.