Black ferrite-based stainless steel sheet

Patent metadata

Field	Value
Publication number	US-11326236-B2
Application number	US-201816486956-A
Country	US
Kind code	B2
Filing date	Jan 26, 2018
Priority date	Feb 23, 2017
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

Provided is a black stainless steel sheet that has excellent weldability, that can ensure good toughness and corrosion resistance, and that can maintain the blackness of the surface thereof, even after being welded. This black ferrite-based stainless steel sheet having excellent weldability includes, as a base, a stainless steel containing, in mass %, 0.020% or less of C, 1.0% or less of Si, 0.35% or less of Mn, 0.04% or less of P, 0.005% or less of S, 11-25% of Cr, 1.0% or less of Mo, 0.020% or less of N, 0.4% or less of Al, 10(C+N) to 0.3% of Ti, 0.05% or less of Nb, and 0.01% or less of O, and has a surface in which an oxide coating is formed on the base, wherein the surface has a lightness index (L*) satisfying L*≤45, chromaticity indices (a*, b*) satisfying −5≤a*≤5 and −5≤b*≤5, and a blackness (E) satisfying E=(L*2+a*2+b*2)1/2≤45.

First claim

The invention claimed is:

1. A black ferrite-based stainless steel sheet, comprising, as a base, a stainless steel containing, in mass %, 0.020% or less of C, 1.0% or less of Si, 0.35% or less of Mn, 0.04% or less of P, 0.005% or less of S, 17-25% of Cr, 0.60% or less of Mo, 0.020% or less of N, 0.4% or less of Al, 10(C+N) to 0.3% of Ti, 0.05% or less of Nb, 0.01% or less of O, and the balance comprising Fe and impurities, and having a surface in which an oxide coating is formed on the base,
wherein the surface has a lightness index (L*) satisfying L*≤45, chromaticity indices (a*, b*) satisfying −5≤a*≤5 and −5≤b*≤5, and a blackness (E) satisfying E=(L* 2 +a* 2 +b* 2 ) 1/2 ≤45, and
wherein a difference in blackness between a flat portion in the stainless steel sheet before being welded and a welding heat-affected portion in the stainless steel sheet welded is 5 or less, and a difference in pitting potential between the flat portion and the welding heat-affected portion in the stainless steel sheet welded is 50 mV or less.

2. The black ferrite-based stainless steel sheet according to claim 1 , wherein the stainless steel contains one or more selected from, in mass %, 1.0% or less of Ni, 1.0% or less of Cu, 1.0% or less of V, and 0.01% or less of B.

3. The black ferrite-based stainless steel sheet according to claim 1 , wherein the stainless steel contains one or more selected from, in mass %, 0.01% or less of Ca, 0.01% or less of REM, and 0.1% or less of Zr.

4. A welded structure comprising the black ferrite-based stainless steel sheet according to claim 1 .

5. The black ferrite-based stainless steel sheet according to claim 2 , wherein the stainless steel contains one or more selected from, in mass %, 0.01% or less of Ca, 0.01% or less of REM, and 0.1% or less of Zr.

6. A welded structure comprising the black ferrite-based stainless steel sheet according to claim 2 .

7. A welded structure comprising the black ferrite-based stainless steel sheet according to claim 3 .

8. A welded structure comprising the black ferrite-based stainless steel sheet according to claim 5 .

Assignees

• Nippon Steel Stainless Steel Corp

Inventors

• Tai Yoshikazu
• Saida Tomoaki
• Imakawa Kazunari
• Suzuki Satoshi

Classifications

• C22C38/26

  with niobium or tantalum · CPC title

• C22C38/40

  with nickel · CPC title

• B23K9/0026

  specially adapted for particular articles or work · CPC title

• B23K2103/05

  Stainless steel · CPC title

• C22C38/28

  with titanium or zirconium · CPC title