PURPOSE: To provide an alloy having improved stress corrosion cracking resistance for high strength oil well pipe under adverse environments by specifying the contents of Ni, Cr, Mn, Mo, W, etc. in steel and the relations among respective additive components.
CONSTITUTION: An alloy consisting of ≤0.1wt% C, ≤1.0% Si, 3W20% Mn, ≤0.030% P, ≤0.005% S, ≤0.5% solAl, ≥1 kind of 20W60% Ni, 15W30% Cr, ≤12% Mo and ≤24% W and the balance Fe and unavoidable impurities. The alloy of the compsn. wherein the conditions ≥110% Cr%+10Mo%+5W%, ≥30% 1/2Mn%+Ni%, and ≤12% 8%≤Mo%+1/2W% are satisfied. If necessary, Cu, Co, rare earth elements, Y, Mg, Ti, etc. are contained in this alloy. The alloy for oil well pipes having the high strength that withstands petroleum excavation in deep wells and severe working environments sufficiently and superior stress corrosion cracking resistance is obtained.
YOSHIKAWA KUNIHIKO
OOTANI YASUO
KUDOU TAKEO
IKEDA AKIO
MOROISHI DAIJI
