Stainless steel sheet and method of manufacturing the same, separator for solid polymer fuel cell, solid polymer fuel cell, and solid polymer fuel cell battery

Patent metadata

Field	Value
Publication number	US-11326224-B2
Application number	US-201716648624-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Sep 19, 2017
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

Provided are a stainless steel sheet with good corrosion resistance, low contact resistance and good press workability without the use of expensive materials such as gold or rare metals, and a method of manufacture the same. A method of manufacturing a stainless steel sheet includes: preparing a slab having a chemical composition including, in mass %: 20 to 26% Cr, up to 0.1% N, up to 2.0% Si, etc. (step S1); performing hot rolling and cold rolling on the slab to produce a rolled steel sheet with a thickness of 50 to 200 μm (step S2); an annealing step in which the rolled steel sheet is annealed and cooled in a gas atmosphere containing nitrogen (step S3); and pickling the rolled steel sheet after the annealing step with a solution containing a non-oxidizing acid (step S4). The stainless steel sheet has an N content of 0.6 to 2.0% by mass.

First claim

The invention claimed is:

1. A stainless steel sheet having a chemical composition of, in mass %:
20 to 26% Cr;
0.6 to 2.0% N;
up to 2.0% Si;
up to 0.040% C;
up to 0.030% P;
up to 0.030% S;
up to 1.5% Mn;
up to 0.50% Cu;
up to 0.50% Mo;
up to 0.10% Ni;
lower than 50 ppm Ca;
lower than 300 ppm sol. Al; and
balance Fe and impurities,
the stainless steel sheet having a thickness of 50 to 200 μm,
a microstructure of teh stainless steel sheet being an austenite single phase,
an average crystal grain size of austenite crystal grains being one half or less of a thickness of the stainless steel sheet,
a surface of the stainless steel sheet having a Cr nitride layer,
wherein Cr, Fe and N contents obtained by glow discharge optical emission spectroscopy of the surface of the stainless steel sheet, as determined by an analysis along a depth direction of a sputter-depth range of 0 to 0.5 μm, satisfy the following expressions, (1) and (2):
0.1≤Cr/Fe≤0.5  (1), and

Cr/N≤1.8  (2),

wherein Cr, Fe and N in expressions (1) and (2) represent Cr, Fe and N contents, in atomic percentage, obtained by glow discharge optical emission spectroscopy of the surface of the stainless steel sheet.

2. A separator for a solid polymer fuel cell comprising the stainless steel sheet according to claim 1 .

3. A solid polymer fuel cell comprising the separator for a solid polymer fuel cell according to claim 2 .

4. A solid polymer fuel cell battery comprising a plurality of solid polymer fuel cells, each according to claim 3 .

5. A method of manufacturing the stainless steel sheet of claim 1 , comprising:
preparing a slab having a chemical composition of, in mass %: 20 to 26% Cr; up to 0.1% N; up to 2.0% Si; up to 0.040% C; up to 0.030% P; up to 0.030% S; up to 1.5% Mn; up to 0.50% Cu; up to 0.50% Mo; up to 0.10% Ni; lower than 50 ppm Ca; lower than 300 ppm sol. Al; and balance Fe and impurities;
performing hot rolling and cold rolling on the slab to produce a rolled steel sheet with a thickness of 50 to 200 μm;
an annealing step in which the rolled steel sheet is annealed and cooled in a gas atmosphere containing nitrogen, wherein a ratio of partial pressure of nitrogen to total pressure of process gas is 0.4 to 0.7, annealing occures at a temperature of 950 to 1200°C. with a holding time of 300 to 900 seconds; and
pickling the rolled steel sheet after the annealing step with a solution containing a non-oxidizing acid,
the stainless steel sheet having an N content of 0.6 to 2.0% by mass.

Assignees

• Nippon Steel Stainless Steel Corp

Inventors

• Kaminaka Hideya
• Nishiyama Yoshitaka
• Nose Koichi
• Maki Jun
• Imamura Junko
• MAEJIMA Kohei
• Takashima Yuya

Classifications

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• C22C38/00

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

• C22C38/001 Primary

  containing N · CPC title

• C23G1/08

  Iron or steel · CPC title

• H01M8/1018

  Polymeric electrolyte materials · CPC title