| 摘要 |
An oil well steel pipe to be placed under the ground and be expanded, which comprises a steel having a chemical composition in mass % that C: 0.05 to 0.45%, Si: 0.1 to 1.5%, Mn: 0.1 to 3.0%, ?: 0.03% or less, S: 0.01% or less, sol Al: 0.05% or less, and the balance: Fe and impurities, with the proviso that the amount of N forming a solid solution in the steel is 40 ppm or less. The steel may also contain one or more of specific amounts of V, Ti, Nb, B, Cr, Mo, Ni, Cu and Ca in addition to the above composition. The oil well steel pipe is excellent in the resistance to the sulfide stress cracking after being expanded. |
