HIGH-STRENGTH STEEL PIPE AND METHOD OF HEAT TREATMENT THEREFOR

摘要

A method of heat treatment for high-strength steel pipe that not only ensures secondary workability but also realizes a satisfactory pressure resisting performance capable of coping with recent-year high pressurization of common rail fuel injection system. A treatment object steel pipe is provided by drawing a steel pipe from steel material loaded at least with vanadium to desired size. The treatment object steel pipe is normalized by maintaining the treatment object steel pipe at high temperature falling within 950° to 1100°C for a given period of time and slowly cooling the steel pipe at given cooling rate, and is tempered by heating the treatment object steel pipe to temperature falling within 500° to 700°C and cooling the steel pipe to ordinary temperature at an arbitrary cooling rate.