| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-carbon seamless steel pipe superior in secondary workability, and a manufacturing method therefor. SOLUTION: The high-carbon seamless steel pipe comprises employing a raw material for the steel pipe, which has a composition of 0.8-1.2% C, 2% or less Si, 3% or less Mn, and 2% or less Cr, reduction rolling the steel pipe within 700 deg.C or higher but 850 deg.C or lower at a cumulative diameter reduction rate of 20-50%, and then cooling it at a cooling rate of 15 deg.C or less, to make the structure have a spheroidizing rate of the carbides of 80% or more, which is defined as (the number of carbides having an aspect ratio of 2 or less)/(the number of all carbides)}×100, and have an average particle diameter of the carbides of 0.5μm or less. Thereby, the material is softened, and the secondary workability such as machinability is remarkably improved.
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