| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive roller bearing of high quality with the long life, through clarifying a relationship between a central segregation rate of carbon (C/C<SB>0</SB>) in a material composing a steel ball as a rolling body in a roller bearing and the finished product, and the rolling life. SOLUTION: The material composing the steel ball is made from a wire rod of a bearing steel, which is continuously cast while being electromagnetically stirred and lightly pressed in the last period of solidification; has the central segregation rate of carbon in the above material and the above finished steel ball so as to satisfy 0.90≤C/C<SB>0</SB>≤1.10, (wherein C/C<SB>0</SB>means the central segregation rate of carbon; and C means a carbon concentration (wt.%) in a central part; and C<SB>0</SB>means an average carbon concentration (wt.%)); has an oxygen content of 10 ppm or less in the above wire rod of the bearing steel; and has a sulfur content of 0.008 wt.% or less in the above wire rod of the bearing steel, to improve the rolling life by inhibiting flaking and cracking from occurring in a local part of the above steel ball in service. COPYRIGHT: (C)2004,JPO
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