HIGH TENSION STEEL FOR LINE PIPE WITH SUPERIOR RESISTANCE TO CRACKING DUE TO HYDROGEN EMBRITTLEMENT

摘要

PURPOSE:To obtain a steel capable of perfectly preventing cracking due to hydrogen embrittlement in the segregation zone by adding Cr as a reinforcing component to a high tension steel for a line pipe having a specified composition in place of Mn which is liable to segregate. CONSTITUTION:This high tension steel for a line pipe consists of, by weight, 0.05-0.20% C, 0.01-0.50% Si, 0.10-0.50% Mn, =0.020% P, =0.005% S, 0.01- 0.10% Al, 0.80-2.0% Cr, 0.001-0.005% Ca and the balance Fe. An abnormal rise in the hardness of the segregation zone of the steel is inhibited, and the amount of MnS in the zone is reduced, so the resistance to cracking due to hydrogen embtittlement is improved. The steel has necessary strength and toughness.