| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a long, large diameter, and thin-walled seamless steel pipe having little bending in a longitudinal direction. SOLUTION: In a heat-treatment for annealing the seamless steel pipe 2 produced with a Mannesman method, while rotating the seamless steel pipe 6 at≥5 rpm around the center axis, the outer surface is cooled from the upper and the lower directions with a cooling device 5 by shifting at≤0.5 m/min speed in the axial direction of the seamless steel pipe 2. The above seamless steel pipe 2 is the long, large diameter, and thin-walled seamless steel pipe having≥3 m length (L),≥70 mm outer diameter (D) and≥10 the ratio (D/t) of the outer diameter (D)/the thickness (t). COPYRIGHT: (C)2005,JPO&NCIPI
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