BEARING PART AND ROLLING BEARING
摘要:
A bearing part (10) is composed of a steel, and has a quench-hardened layer (11) in a surface of the bearing part. The quench-hardened layer includes a plurality of martensite crystal grains. The plurality of martensite crystal grains are classified into a first group and a second group. A minimum value of crystal grain sizes of the martensite crystal grains belonging to the first group is larger than a maximum value of crystal grain sizes of the martensite crystal grains belonging to the second group. A value obtained by dividing a total area of the martensite crystal grains belonging to the first group by the total area of the plurality of martensite crystal grains is more than or equal to 0.3. A value obtained by dividing, by the total area of the plurality of martensite crystal grains, a total area of the martensite crystal grains belonging to the first group except for a martensite crystal grain that has a minimum crystal grain size and that belongs to the first group is less than 0.3. An average grain size of the martensite crystal grains belonging to the first group is less than or equal to 1.5 μm. The quench-hardened layer (11) further includes a plurality of cementite grains. A number density of cementite grains each having a grain size of more than or equal to 1 μm is more than or equal to 0.025/μm2.
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