High-strength stainless steel pipe

Patent metadata

Field	Value
Publication number	US-10151012-B2
Application number	US-201414916265-A
Country	US
Kind code	B2
Filing date	Aug 4, 2014
Priority date	Sep 4, 2013
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

A method of manufacturing a high-strength stainless steel pipe includes forming a steel pipe having a predetermined size, the steel having a composition comprising by mass % 0.005 to 0.05% C, 0.05 to 1.0% Si, 0.2 to 1.8% Mn, 0.03% or less P, 0.005% or less S, 14 to 20% Cr, 1.5 to 10% Ni, 1 to 5% Mo, 0.5% or less V, 0.15% or less N, 0.01% or less O, 0.002 to 0.1% Al, and Fe and unavoidable impurities as a balance; applying a quenching treatment two times or more to the steel pipe where the steel pipe is quenched by reheating to a temperature of 750° C. or above and cooling to a temperature of 100° C. or below at a cooling rate equal to or higher than an air-cooling rate; and applying a tempering treatment where the steel pipe is tempered at a temperature of 700° C. or below.

First claim

The invention claimed is:

1. A high-strength stainless steel pipe having:
a composition containing by mass % 0.005 to 0.05% C, 0.05 to 1.0% Si, 0.2 to 1.8% Mn, 0.03% or less P, 0.005% or less S, 14 to 20% Cr, 1.5 to 10% Ni, 1 to 5% Mo, 0.5% or less V, 0.15% or less N, 0.01% or less 0, 0.002 to 0.1% Al, and Fe and unavoidable impurities as a balance,
a thickness of 19.1 mm or more,
a Charpy absorbed energy of 30 J or more at a temperature of −10° C., and
a sulfide stress corrosion cracking resistance, wherein a specimen is not broken for 720 hours or more in a sulfide stress corrosion cracking test which is performed under a condition where a round bar specimen cut out from the high-strength stainless steel pipe conforming to a provision of a NACE-TM0177 Method A is soaked into an aqueous solution prepared by adding an acetic acid and sodium acetate to 20 mass % NaCl aqueous solution (in an atmosphere where a liquid temperature is 20° C., H 2 S is at 0.1 atm and CO 2 is at 0.9 atm) and controlling a pH value thereof to 3.5, and an applied stress is 90% of a yield stress,
wherein the steel pipe has a microstructure containing ferrite and martensite, the martensite having an average grain size of 6.0 μm or below the ferrite and martensite forming a ferrite-martensite interface,
wherein a content of Mo in the ferrite-martensite interface is three or more times as large as a content of Mo of the steel pipe, and
wherein the composition further contains 3% or less W, and a content of W in the ferrite-martensite interface is three or more times as large as a content of W of the steel pipe.

2. The high-strength stainless steel pipe according to claim 1 , comprising a composition further containing at least one group selected from the groups A to C consisting of:
Group A: from 3.5% or less Cu by mass %;
Group B: at least one selected from 0.5% or less Nb, 0.3% or less Ti and 0.01% or less B, by mass %; and
Group C: at least one selected from 0.01% or less Ca, 0.01 or less REM and 0.2% or less Zr, by mass %.

Assignees

• Jfe Steel Corp

Inventors

• Eguchi Kenichiro
• Ishiguro Yasuhide
• Suzuki Takeshi
• Sato Hideo
• Nakahashi Tetsu

Classifications

• C21D8/10

  during manufacturing of tubular bodies · CPC title

• C22C38/40

  with nickel · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/54

  with boron · CPC title

• C22C38/00

  Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) · CPC title