Production method of electric resistance welded steel pipe corrosion resistance steel for excellent low temperature toughness

摘要

PROBLEM TO BE SOLVED: To provide a corrosion resisting steel for electric resistance welded tube, capable of securing HIC resistance and removing toughness deterioration in a resistance welded zone by specifying respective contents of C, Si, Mn, P, S, Al, and Ca in the steel and also specifying the ratio between the contents of Ca and O. ;SOLUTION: The steel for electric resistance welded tube has a composition consisting of 0.01-0.20% C, 0.01-0.50% Si, 0.50-1.80% Mn, ≤0.020% P, ≤0.001% S, 0.005-0.100% Al, 0.0005-0.0050% Ca, and the balance Fe with inevitable impurities. In this composition, the ratio between the contents of Ca and O, (Ca)/(O), is regulated to 1.5-2.0, and further, one or ≥2 kinds among 0.20-0.80% Cu, 0.05-0.60% Ni, ≤1.00% Cr, ≤1.00% Mo, 0.01-0.10% Ti, 0.01-0.10% Nb, and 0.10% V are incorporated at need. Moreover, it is desirable to regulate the amount of O in the molten steel before the addition of Ca and Si to ≤0.0020%.;COPYRIGHT: (C)1997,JPO