| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel pipe used in an oil well of a crude oil or a natural gas and in a gas well, particularly a high-strength stainless steel pipe superior in corrosion resistance for the oil well. SOLUTION: This steel pipe has a composition comprising 0.05% or less C, 0.50% or less Si, 0.10-1.80% Mn, 0.03% or less P, 0.005% or less S, 14.0-17.0% Cr, 5.0-8.0% Ni, 1.0-3.5% Mo, 0.5-3.5% Cu, 0.05% or less Al, 0.20% or less V, 0.03-0.15% N, 0.006% or less O, further one or two elements selected from 0.2% or less Nb and 0.3% or less Ti, and the balance Fe with unavoidable impurities; and has a structure containing an MC-type carbonitride of a precipitate, which occupies 3.0 mass% or more of all the precipitates. Thereby, the steel pipe for the oil well acquires high strength and superior corrosion resistance. The steel pipe may include Ca, or one or more elements selected among Zr, B and W. COPYRIGHT: (C)2005,JPO&NCIPI
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