Patent ID: 6090230
Filing Date: 2000-07-18
Classification: C21D

Abstract:
A method of cooling a steel pipe, while rotating the pipe around the axis of the pipe, wherein cooling water is made to flow down or sprayed to the outer surface of a martensitic stainless steel pipe, cooling water is passed through the inside of the pipe with a wetting angle no more than 220.degree., the cooling rate at the inner surface is made substantially equal to that at the outer surface, the maximum cooling rate at the inner and the outer surfaces of the steel pipe is set to 35.degree. C./s or lower, and the cooling rate is set to 8.degree. C./s or higher in a temperature region from the central temperature between Ms point and Mf point to the Mf point at the portion at which the cooling rate is minimum thereby cooling the martensitic stainless steel pipe.