| 摘要 |
PURPOSE:To provide a steel for rolling parts capable of improving the strength of the rolling parts for bearing, formed by means of cold working, to the extent equal to or higher than the conventional machined parts by controlling the length and number of sulfide type inclusions in the steel to the values in optimum ranges, respectively. CONSTITUTION:By exerting forming by means of cold working so that the maximum length of the sulfide type inclusions in the steel for rolling parts is regulated to <=100mum and also the number of the above inclusions having a length exceeding 40mum is regulated to <=50 per unit area (160mm<2>), the roughness of the bore surface is improved and strength is increased and, as a result, fatigue cracking life longer than that of a bearing ring formed by means of machining can be obtained.
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