HIGHLY CORROSION RESISTANT TI-CONTAINING ALLOY FOR OIL WELL TUBE AND LINE PIPE EXCELLENT IN HOT WORKABILITY

摘要

PURPOSE:To obtain a highly corrosion resistant alloy steel excellent in hot workability by incorporating specific amounts of Ti to an Ni-Cr-Mo alloy steel for use in oil well tube, etc., and limiting the contents of Si and Mn to specific values, respectively, according to Ti content. CONSTITUTION:As a highly corrosion resistant alloy for oil well tube and line pipe for use in oil fields containing H2S, CO2, etc., an Ni-Cr-Mo alloy steel having a composition consisting of, by weight, 0.5-2% Ti, 0.03% C, 0.35% Si, 0.45% Mn, 0.01% P, 0.0010% S, 25-62% Ni, 20-26% Cr, 2.5-9% Mo, 0.1% Al, 0.0010-0.01% Ca, 0.03% N, and the balance Fe is used. At this time, respective contents of Si and Mn are limited according to Ti content so that inequalities I, II are satisfied. By this method, the alloy steel for oil well tube and line pipe excellent in hot workability as well as in corrosion resistance and strength can be obtained.