Ferritic stainless steel having excellent salt corrosion resistance

Patent metadata

Field	Value
Publication number	US-11286547-B2
Application number	US-201916966426-A
Country	US
Kind code	B2
Filing date	Mar 19, 2019
Priority date	Mar 30, 2018
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

This ferritic stainless steel includes: in terms of % by mass, C: 0.001% to 0.100%; Si: 0.01% to 5.00%; Mn: 0.01% to 2.00%; P: 0.050% or less; S: 0.0100% or less; Cr: 9.0% to 25.0%; Ti: 0.001% to 1.00%; Al: 0.001% to 5.000%; and N: 0.001% to 0.050%, with a balance being Fe and impurities, wherein in a region from a steel surface to a depth of 5 nm, and not exceeding a thickness of a passive film, a total amount of Al and Si is 1.0 atomic % or more, an amount of Cr is 10.0 atomic % or more, and an amount of Fe is 85.0 atomic % or less, in terms of cation fraction.

First claim

The invention claimed is:

1. A ferritic stainless steel having excellent corrosion resistance against salt damage, comprising: in terms of % by mass,
C: 0.001% to 0.100%;
Si: 0.01% to 5.00%;
Mn: 0.01% to 2.00%;
P: 0.050% or less;
S: 0.0100% or less;
Cr: 9.0% to 25.0%;
Ti: 0.001% to 1.00%;
Al: 1.050% to 5.000%;
N: 0.001% to 0.050%;
Ni: 0% to 1.00%;
Mo: 0% to 3.00%;
Sn: 0% to 1.000%;
Cu: 0% to 2.00%;
B: 0% to 0.0050%;
Nb: 0% to 0.500%;
W: 0% to 1.000%;
V: 0% to 0.500%;
Sb: 0% to 0.100%;
Co: 0% to 0.500%;
Ca: 0% to 0.0050%;
Mg: 0% to 0.0050%;
Zr: 0% to 0.0300%;
Ga: 0% to 0.0100%;
Ta: 0% to 0.050%; and
REM: 0% to 0.100%,
with a balance being Fe and impurities,
wherein a passive film is present in a steel surface, and
in a region ranging from the steel surface to a depth of 5 nm, and not exceeding a thickness of the passive film, Al and Si are present in a total amount of 1.0 atomic % or more, Cr is present in an amount of 10.0 atomic % or more, and Fe is present in an amount of 85.0 atomic % or less, in terms of cation fraction.

2. The ferritic stainless steel having excellent corrosion resistance against salt damage according to claim 1 ,
wherein after the ferritic stainless steel is subjected to a heat treatment at 400° C. for 8 hours in air, a concentrated layer of Al and Si is present at an interface between a base material and an oxide film at a volume ratio of 10% or more.

3. The ferritic stainless steel having excellent corrosion resistance against salt damage according to claim 1 , comprising: in terms of % by mass, one or more selected from the group consisting of:
Ni: 0.01% to 1.00%,
Mo: 0.01% to 3.00%,
Sn: 0.001% to 1.000%,
Cu: 0.01% to 2.00%,
B: 0.0001% to 0.0050%,
Nb: 0.001% to 0.500%,
W: 0.001% to 1.000%,
V: 0.001% to 0.500%,
Sb: 0.001% to 0.100%, and
Co: 0.001% to 0.500%.

4. The ferritic stainless steel having excellent corrosion resistance against salt damage according to claim 1 , comprising: in terms of % by mass, one or more selected from the group consisting of:
Ca: 0.0001% to 0.0050%,
Mg: 0.0001% to 0.0050%,
Zr: 0.0001% to 0.0300%,
Ga: 0.0001% to 0.0100%,
Ta: 0.001% to 0.050%, and
REM: 0.001% to 0.100%.

5. The ferritic stainless steel having excellent corrosion resistance against salt damage according to claim 2 , comprising: in terms of % by mass, one or more selected from the group consisting of:
Ni: 0.01% to 1.00%,
Mo: 0.01% to 3.00%,
Sn: 0.001% to 1.000%,
Cu: 0.01% to 2.00%,
B: 0.0001% to 0.0050%,
Nb: 0.001% to 0.500%,
W: 0.001% to 1.000%,
V: 0.001% to 0.500%,
Sb: 0.001% to 0.100%, and
Co: 0.001% to 0.500%.

6. The ferritic stainless steel having excellent corrosion resistance against salt damage according to claim 2 , comprising: in terms of % by mass, one or more selected from the group consisting of:
Ca: 0.0001% to 0.0050%,
Mg: 0.0001% to 0.0050%,
Zr: 0.0001% to 0.0300%,
Ga: 0.0001% to 0.0100%,
Ta: 0.001% to 0.050%, and
REM: 0.001% to 0.100%.

7. The ferritic stainless steel having excellent corrosion resistance against salt damage according to claim 3 , comprising: in terms of % by mass, one or more selected from the group consisting of:
Ca: 0.0001% to 0.0050%,
Mg: 0.0001% to 0.0050%,
Zr: 0.0001% to 0.0300%,
Ga: 0.0001% to 0.0100%,
Ta: 0.001% to 0.050%, and
REM: 0.001% to 0.100%.

Assignees

• Nippon Steel Stainless Steel Corp

Inventors

• Abe Masatoshi
• Hamada Junichi
• Hiraide Nobuhiko
• HAYASHI Atsutaka

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C21D8/1244

  characterised by the heat treatment · CPC title

• C21D9/46

  for sheet metals · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/60

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title