Anti-collapse oil casing with high strength and manufacturing method therefor

Abstract

An anti-collapse oil casing with high strength and a manufacturing method therefor, comprising the following chemical elements in percentage by mass: C: 0.08%-0.18%; Si: 0.1%-0.4%; Mn: 0.1%-0.28%; Cr: 0.2%-0.8%; Mo: 0.2%-0.6%; Nb: 0.02%-0.08% b; V: 0.01%-0.15%; Ti: 0.02%-0.05%; B: 0.0015%-0.005%; and Al: 0.01%-0.05%. The manufacturing method for the anti-collapse oil casing with high strength comprises the steps of: (1) smelting and continuous casting; (2) perforating, rolling, and sizing; (3) controlled cooling: the initial cooling temperature being Ar3+50° C. and the final cooling temperature being ≤80° C.; the cooling step being performed only to the outer surface of the casing without performing to the inner wall of the casing; and the rate of the controlled cooling being 30-70° C./s; (4) tempering; and (5) thermal straightening. The anti-collapse oil casing with high strength according to the present invention has reasonable chemical composition and process design, which not only has excellent economic efficiency, but also has high strength, high toughness and high anti-collapse performance.