METHOD FOR MANUFACTURING SEAMLESS STEEL TUBE

摘要

PROBLEM TO BE SOLVED: To provide a method for stably manufacturing the seamless steel tube made of high-alloy steel without performing heavy investment of equipment in the manufacturing line of the seamless steel tube constituting of an inclined piercing mill and a mandrel mill. SOLUTION: In the manufacturing line of the seamless steel tube constituting of the inclined piercing mill and the mandrel mill, a billet 1 on which machining for providing an axisymmetric recessed part 4 is preliminarily performed at the rear end part 3 of the billet before piercing is used. The recessed part 4 is machined so that the thickness in the rear end part 3 of the billet is≥10 mm. COPYRIGHT: (C)2004,JPO