PRECIPITATION HARDENING TYPE ALLOY FOR HIGH STRENGTH OIL WELL PIPE WITH SUPERIOR STRESS CORROSION CRACKING RESISTANCE

摘要

PURPOSE:To obtain a precipitation hardening type alloy for a high strength oil well pipe with superior stress corrosion cracking resistance by adding C, Si, Mn, P, S, N, Ni, Cr, Nb, etc. in a specified ratio. CONSTITUTION:An alloy consisting of, by weight, =0.1% C, =1.0% Si, =2.0% Mn, =0.030% P, =0.005% S, 0.05-0.25% N, 30-60% Ni, 15-35% Cr, =12% Mo and/or =24% W, and the balance Fe with inevitable impurities while satisfying Cr%+10Mo%+5W%=110% and 7.5%=Mo+1/2W%=12% is prepared. To said composition may be added =2% Cu and/or =2% Co, and/or 1 or =2 kinds of elements selected from =0.1% rare earth element, =0.20% Y, =0.10% Mg and =0.10% Ca.