STEEL OIL WELL PIPE HAVING EXCELLENT SULFIDE STRESS CRACKING RESISTANCE

摘要

Provided is a steel oil well pipe which has excellent sulfide stress cracking resistance (SSC resistance). A steel oil well pipe of the present invention contains, in mass%, 0.15-0.35% of C, 0.1-0.75% of Si, 0.1-1.0% of Mn, 0.1-1.7% of Cr, 0.1-1.2% of Mo, 0.01-0.05% of Ti, 0.010-0.030% of Nb, 0.01-0.1% of Al, 0.03% or less of P, 0.01% or less of S, 0.007% or less of N and 0.01% or less of O, with the balance made up of Fe and impurities. The Ti content and the Nb content in the residue obtained by bromine-methanol extraction satisfy the following formula (1). 100 × [Nb]/([Ti] + [Nb]) = 27.5 (1) In this connection, the Ti content (mass%) and the Nb content (mass%) in the residue are respectively assigned to [Ti] and [Nb].