| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a bend steel tube capable of preventing simply and surely generation of a scale on the inner surface of the steel tube by heat treatment or bending under heating of the steel tube for the bend steel tube, and dispensing with a removal step of an inside scale by polishing, acid cleaning or the like.SOLUTION: Both ends of a corrosion-resistant steel tube or a two-layer steel tube having a corrosion-resistant steel tube as an inner layer and a carbon steel tube as an outer layer are sealed, and the inside of the sealed steel tube is deaerated, and the whole circumference of a part in the axial direction is heated, while moving the deaerated steel tube in the axial direction, and while applying bending stress to the heated part, bending and heat treatment (hardening) is applied thereto. |
