CR-MO STEEL FOR PRESSURE CONTAINER EXCELLENT IN HYDROGEN CORROSION RESISTANT CHARACTERISTICS AND SR CRACK-RESISTANT

摘要

PURPOSE:To provide Cr-Mo steel for a pressure container enhanced in hydrogen corrosion resistant characteristics and SR crack resistance characteristics, in Cr-Mo steel having a specific composition, by especially limiting the value of S-parameter-P in impurities to a definite amount or less. CONSTITUTION:Cr-Mo steel consists of, on a wt. basis, 0.07-0.18% C, 0.05-1.0% Mn, 0.6-6.0% Cr, 0.3-1.5% Mo, 0.0003-0.010% B, 0.003-0.2% acid sol. Al, below 0.10% Si, according to necessity, one or more of elements selected from a group comprising 0.50% or less V, 0.20% or less Nb, 0.20% or less Ti and 0.20% or less Zr and the remainder of substantially Fe and the value of S-parameter-P of this steel shown by formula P=S-32/40 Ca-32/140 REM is limited to 0.0010% or less. By this steel composition, the hydrogen corrosion resistance characteristics and SR crack resistant characteristics of Cr-Mo steel for a pressure container used under a high temp. and high pressure hydrogen environment can be improved.