Martensitic stainless steel pipe and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-2022195610-A1
Application number	US-202017594934-A
Country	US
Kind code	A1
Filing date	Jul 17, 2020
Priority date	Jul 24, 2019
Publication date	Jun 23, 2022
Grant date	—

Abstract

A method of manufacturing a martensitic stainless steel pipe includes: preparing a hollow shell, S1; a pickling step, S3-2, in which the hollow shell is immersed in nitrohydrofluoric acid solution at a temperature below 50° C.; after pickling step S3-2, a high-pressure water washing step, S4, in which high-pressure water is injected onto the outer surface of the hollow shell to clean the outer surface of the hollow shell; after high-pressure water washing step S4, a hot-water immersion step, S5, in which the hollow shell is immersed in hot water if necessary; and spraying gas onto the surface of the hollow shell, S6, before a lapse of 15 minutes from completion of high-pressure water washing step S4 or hot-water immersion step S5.

First claim

1 . A method of manufacturing a martensitic stainless steel pipe, comprising:
preparing a hollow shell having a chemical composition of, in mass %: 0.001 to 0.050% C; 0.05 to 1.00% Si; 0.05 to 1.00% Mn; up to 0.030% P; up to 0.0020% S; below 0.50% Cu; 11.50 to below 14.00% Cr; above 5.00 to 7.00% Ni; above 1.00 to 3.00% Mo; 0.02 to 0.50% Ti; 0.001 to 0.100% Al; 0.0001 to 0.0040% Ca; 0.0001 to below 0.0200% N; 0 to 0.500% V; 0 to 0.500% Nb; 0 to 0.500% Co; and balance Fe and impurities; a pickling step in which the hollow shell is immersed in nitriohydrofluoric acid solution at a temperature below 50° C.; after the pickling step, a high-pressure water washing step in which high-pressure water is injected onto an outer surface of the hollow shell to clean the outer surface of the hollow shell; and a gas spraying step in which the outer surface of the hollow shell is sprayed with gas before a lapse of 15 minutes from completion of the high-pressure water washing step.

2 . A method of manufacturing a martensitic stainless steel pipe comprising:
preparing a hollow shell having a chemical composition of, in mass %: 0.001 to 0.050% C; 0.05 to 1.00% Si; 0.05 to 1.00% Mn; up to 0.030% P; up to 0.0020% S; below 0.50% Cu; 11.50 to below 14.00% Cr; above 5.00 to 7.00% Ni; above 1.00 to 3.00% Mo; 0.02 to 0.50% Ti; 0.001 to 0.100% Al; 0.0001 to 0.0040% Ca; 0.0001 to below 0.0200% N; 0 to 0.500% V; 0 to 0.500% Nb; 0 to 0.500% Co; and balance Fe and impurities; a pickling step in which the hollow shell is immersed in nitrohydrofluoric acid solution at a temperature below 50° C.; after the pickling step, a high-pressure water washing step in which high-pressure water is injected onto an outer surface of the hollow shell to clean the outer surface of the hollow shell; after the high-pressure water washing step, a hot-water immersion step in which the hollow shell is immersed in hot water; and a gas spraying step in which the outer surface of the hollow shell is sprayed with gas before a lapse of 15 minutes from completion of the hot-water immersion step.

3 . The method of manufacturing a martensitic stainless steel pipe according to claim 1 , wherein, at the pickling step, the hollow shell is immersed in nitriohydrofluoric acid solution at a temperature below 30° C.

4 . A martensitic stainless steel pipe having a chemical composition of, in mass %:
0.001 to 0.050% C; 0.05 to 1.00% Si; 0.05 to 1.00% Mn; up to 0.030% P; up to 0.0020% S; below 0.50% Cu; 11.50 to below 14.00% Cr; above 5.00 to 7.00% Ni; above 1.00 to 3.00% Mo; 0.02 to 0.50% Ti; 0.001 to 0.100% Al; 0.0001 to 0.0040% Ca; 0.0001 to below 0.0200% N; 0 to 0.500% V; 0 to 0.500% Nb; 0 to 0.500% Co; and balance Fe and impurities, wherein the martensitic stainless steel pipe satisfies the following expressions, (1), (2) and (3), and excludes a case satisfying R=G=B=255:
154≤ B≤ 255  (1)

146≤ R≤ 255  (2)

142≤ G≤ 255  (3),

in the expressions, B indicates a value of a blue component on a 256-level gray scale from 0 to 255, the blue component being one of three components, red, green and blue, obtained by measurement on an outer surface of the martensitic stainless steel pipe; R indicates a value of a red component on a 256-level gray scale from 0 to 255, the red component being one of the three components, red, green and blue, obtained by measurement of the outer surface of the martensitic stainless steel pipe; and G indicates a value of a green component on a 256-level gray scale from 0 to 255, the green component being one of the three components, red, green and blue, obtained by measurement of the outer surface of the martensitic stainless steel pipe.

5 . The martensitic stainless steel pipe according to claim 4 , wherein the martensitic stainless steel pipe excludes a case satisfying the following expression, (4):
504≤( R−G )×( R−B )≤1960  (4).

6 . The martensitic stainless steel pipe according to claim 4 , wherein the martensitic stainless steel pipe satisfies the following expression, (5), and excludes a case satisfying one of the following expressions, (6) and (7):
−48≤( R−G )×( R−B )≤396  (5)
( R−G )×( R−B )=220  (6)
( R−G )×( R−B )=272  (7).

7 . The method of manufacturing a martensitic stainless steel pipe according to claim 2 , wherein, at the pickling step, the hollow shell is immersed in nitrohydrofluoric acid solution at a temperature below 30° C.

Assignees

• Nippon Steel Corp

Inventors

• Noguchi Mikiko
• Yamaguchi Takashi

Classifications

• C21D8/10

  during manufacturing of tubular bodies · CPC title

• C21D9/08

  for tubular bodies or pipes · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C23G3/04

  for cleaning pipes · CPC title

• C23G1/081

  solutions containing H2SO4 · CPC title