| 摘要 |
PROBLEM TO BE SOLVED: To provide high purity bearing steel in which Ti-type inclusions, particularly particles of TiN, which are supposed to greatly affect the acoustic characteristics of balls for miniature bearing can be refined. SOLUTION: Bearing steel containing <=10 ppm, preferably <=7 ppm, Ti and <=50 ppm, preferably <=30 ppm, N is cast into an ingot. The ingot is heated at >=1,200 deg.C, preferably about 1,240 deg.C, for >=1 h to undergo soaking treatment. By this procedure, the ingot becomes virtually free from the presence of TiN particles of >=7.5μm length. As to the size of the ingot, a small-size ingot of <=3.0 tons is preferred.
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