| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot finished seamless steel tube which is less in the dimensional changes caused by the residual strain in the case of grinding inner and outer surfaces of a cut ring used for a bearing race, etc. SOLUTION: In this manufacturing method of the hot finished seamless steel tube less in the dimensional changes during the grinding work, the seamless steel tube is hot worked, and annealed, and straightened, and then, the seamless steel tube is annealed at 520-630 deg.C in order to remove the residual stress generated by the straightening, and subjected to the light straightening by a two-roll air bend type straightening machine shown in Fig. 1 with the offset of <=5 mm, and the crush of 1.5 to 5 mm.
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