Martensitic stainless steel seamless pipe for oil country tubular goods, and method for producing same

Abstract

Provided herein is a martensitic stainless steel seamless pipe, intended for oil country tubular goods, having high strength, and excellent sulfide stress corrosion cracking resistance. A method for producing such a martensitic stainless steel seamless pipe is also provided. The martensitic stainless steel seamless pipe for oil country tubular goods has a composition that contains, in mass %, C: 0.035% or less, Si: 0.5% or less, Mn: 0.05 to 0.5%, P: 0.03% or less, S: 0.005% or less, Cu: 2.6% or less, Ni: 5.3 to 7.3%, Cr: 11.8 to 14.5%, Al: 0.1% or less, Mo: 1.8 to 3.0%, V: 0.2% or less, N: 0.1% or less, and the balance Fe and unavoidable impurities, and in which C, Mn, Cr, Cu, Ni, Mo, W, Nb, N, and Ti satisfy the predetermined relations.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is the U.S. National Phase application of PCT / JP2017 / 033008, filed Sep. 13, 2017, which claims priority to Japanese Patent Application No. 2016-208420, filed Oct. 25, 2016, the disclosures of these applications being incorporated herein by reference in their entireties for all purposes.FIELD OF THE INVENTION[0002]The present invention relates to a martensitic stainless steel seamless pipe for use in oil country tubular goods used in oil well and gas well applications such as in crude oil wells and natural gas wells, and to a method for producing such a martensitic stainless steel seamless pipe. The invention particularly relates to improvement of corrosion resistance in a severe corrosive environment containing carbon dioxide gas (CO2), chlorine ions (Cl−), and the like, and improvement of sulfide stress corrosion cracking resistance (SSC resistance) in a hydrogen sulfide (H2S)-containing environment.BACKGROUND OF THE INVENTION[0003]...

AI Technical Summary

Benefits of technology

[0023]Aspects of the present invention can produce a martensitic stainless steel seamless pipe for oil country tubular goods having excellent sulfide stress corrosion cracking resistance (SSC resistance) in a CO2—, Cl−—, and H2S-containing corrosive environment, and high strength with a yield stress YS of 758 MPa (110 ksi) or more.

Problems solved by technology

However, there is no investigation of sulfide stress corrosion cracking resistance, and the technique cannot be said as providing the level of corrosion resistance that can withstand a severe corrosive environment.

However, these techniques do not investigate sulfide stress corrosion cracking resistance in other atmospheres, and cannot be said as providing the level of sulfide stress corrosion cracking resistance that can withstand the today's more severe corrosive environments.