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

The present invention provides a martensitic stainless steel seamless pipe with high strength and excellent resistance to sulfide stress corrosion cracking (SSC resistance) in a corrosive environment containing CO2, Cl−, and H2S. The invention is achieved by adjusting the composition of a 13% Cr stainless steel pipe with specific amounts of C, Mn, Cr, Cu, Ni, Mo, W, Nb, N, and Ti and subjecting it to appropriate quenching and tempering treatments. The resulting seamless pipe has a yield stress of ≥758 MPa (≥110 ksi) and does not crack after 720 hours under an applied stress close to the yield stress in a test solution containing CO2, Cl−, and H2S.

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.