ULTRA-HIGH-STRENGTH AND ULTRA-HIGH-TOUGHNESS OIL CASING AND MANUFACTURING METHOD THEREOF

摘要

There is disclosed an ultrahigh strength and ultrahigh toughness oil casing pipe, comprising the following chemical elements in mass percentages: C: 0.12-0.18%; Si: 0.1-0.4%; Mn: 1.1-1.6%; Cr: 0.1-0.4%; Mo: 0.2-0.5%; Nb: 0.02-0.04%; Ti: 0.02-0.05%; B: 0.0015-0.005%; Al: 0.01-0.05%; Ca: 0.0005-0.005%; N≦0.008%; with the proviso of 0(Ti—3.4N)≦0.02%, Ti/B≧10; and the balance of Fe and other unavoidable impurities. The strength of the oil casing pipe can be equal to or higher than 150 ksi steel grade, and the zero degree lateral Charpy impact work is not less than 10% of the yield strength of the 150 ksi steel grade.