PROCESS FOR PRODUCING HIGH-STRENGTH SEAMLESS STEEL PIPES EXCELLENT IN SULFIDE STRESS CORROSION CRACKING RESISTANCE

摘要

A process for producing seamless steel pipes to be used as oil well pipes, line pipes, piping for chemical plants, etc. having both high strength and high sulfide stress corrosion cracking resistance by using inexpensive components, which process comprises increasing the content of C and minimizing the contents of impurities such as P and S, conducting quenching at a relatively slow rate of 1 to 50°C/s after heat treatment, then tempering in a relatively high temperature range of from 680°C to the Ac, transformation point. The pipe thus obtained has a yield strength of 75 kgf/mm² or more and excellent stress corrosion cracking resistance without causing any quenching crack.