| 摘要 |
A purpose of the present invention is to provide a martensitic stainless steel tube exhibiting excellent performance even in severe corrosive environments in which a partial pressure of hydrogen sulfide exceeds 0.03 bar. Provided is a low C-high Cr alloy steel tube for OCTG (Oil Country Tubular Goods) having minimum yield strength of 862 MPa and excellent corrosion resistance, wherein the steel tube contains, in percent by mass, 0.005 to 0.05% C, 12 to 16% Cr, 1.0% or less Si, 2.0% or less Mn, 3.5 to 7.5% Ni, 1.5 to 3.5% Mo, 0.01 to 0.05% V, 0.02% or less N, and 0.01 to 0.06% Ta and satisfies the relationship in the following formula (1), and the rest comprises Fe and unavoidable impurities. 25-25 (% Ni)+5 (% Cr)+25 (% Mo)>=0(1) |
