FERRITIC STAINLESS STEEL FOR FUEL CELL AND METHOD FOR PRODUCING THE SAME

• US 20170321310A1
• Filed: 07/29/2015
• Published: 11/09/2017
• Est. Priority Date: 07/29/2014
• Status: Active Grant

• Current Assignee: Nippon Steel Stainless Steel Corporation (Nippon Steel Corporation)
• Original Assignee: Nippon Steel & Sumikin Stainless Steel Corporation (Nippon Steel Corporation)
• Inventors: HATANO, Masaharu, HAYASHI, Atsutaka, MATSUMOTO, Kazuhisa
• Granted Patent: US 10,544,490 B2
• Time in Patent Office: Days
• CPC Class Codes: C21D 1/76 Adjusting the composition of the atmosphere
• CPC Class Codes: C21D 6/00 Heat treatment of ferrous alloys
• CPC Class Codes: C21D 6/002 containing Cr C21D6/004 takes precedence
• CPC Class Codes: C21D 9/46 for sheet metals
• CPC Class Codes: C22C 38/00 Ferrous alloys, e.g. steel alloys cast-iron alloys C22C37/00
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• CPC Class Codes: C22C 38/005 containing rare earths, i.e. Sc, Y, Lanthanides
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/12 containing tungsten, tantalum, molybdenum, vanadium, or niobium
• CPC Class Codes: C22C 38/14 containing titanium or zirconium
• CPC Class Codes: C22C 38/18 containing chromium
• CPC Class Codes: C22C 38/20 with copper
• CPC Class Codes: C22C 38/22 with molybdenum or tungsten
• CPC Class Codes: C22C 38/24 with vanadium
• CPC Class Codes: C22C 38/28 with titanium or zirconium
• CPC Class Codes: C22C 38/38 with more than 1.5% by weight of manganese
• CPC Class Codes: C22C 38/60 containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
• CPC Class Codes: H01M 8/06 : Combination of fuel cells with means for production of reactants or for treatment of residues regenerative fuel cells H01M8/18
• CPC Class Codes: H01M 8/12 : operating at high temperature, e.g. with stabilised ZrO2 electrolyte
• CPC Class Codes: Y02E 60/50 : Fuel cells

Abstract

A ferritic stainless steel for a fuel cell includes, in mass %, Cr: 11 to 25%, C: 0.03% or less, Si: 2% or less, Mn: 2% or less, Al: 0.5 to 4.0%, P: 0.05% or less, S: 0.01% or less, N: 0.03% or less, Ti: 1% or less, and a balance composed of Fe and unavoidable impurities. Furthermore, in the ferritic stainless steel, the maximal concentration of Al in a surface of the ferritic stainless steel is 30 mass % or more in cation ion fraction excepting 0 in an depth direction region having twice a thickness of an oxide film having less than 0.1 μm.

Claims

1. A ferritic stainless steel for a fuel cell comprising, in mass %, Cr:

11 to 25%, C;

0.03% or less, Si;

2% or less, Mn;

2% or less, Al;

0.5 to 4.0%, P;

0.05% or less, S;

0.01% or less, N;

0.03% or less, Ti;

1% or less, and a balance composed of Fe and unavoidable impurities, wherein,

a maximal concentration of Al in a surface of the ferritic stainless steel is 30 mass % or more in cation ion fraction excepting O in an depth direction region having twice a thickness of an oxide film having less than 0.1 μ

m.

2. The ferritic stainless steel for a fuel cell according to claim 1, wherein, a maximal concentration of Ti in a surface of the ferritic stainless steel is 3 mass % or more in cation ion fraction excepting O.

3. The ferritic stainless steel for a fuel cell according to claim 1, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, Sn;

1% or less, Sb;

1% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, Ga;

0.1% or less, Mg;

0.01% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

4. A method for producing the ferritic stainless steel for a fuel cell according to claim 1, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

14. The ferritic stainless steel for a fuel cell according to claim 2, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, Sn;

1% or less, Sb;

1% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, Ga;

0.1% or less, Mg;

0.01% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

15. A method for producing the ferritic stainless steel for a fuel cell according to claim 2, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

16. A method for producing the ferritic stainless steel for a fuel cell according to claim 3, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

17. A method for producing the ferritic stainless steel for a fuel cell according to claim 14, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

5. A ferritic stainless steel for a fuel cell comprising, in mass %, Cr:

11 to 25%, C;

0.03% or less, Si;

2% or less, Mn;

2% or less, Al;

0.5 to 4.0%, P;

0.05% or less, S;

0.01% or less, N;

0.03% or less, Ti;

1% or less, and a balance composed of Fe and unavoidable impurities, wherein,

a maximal concentration of Al in a surface of the ferritic stainless steel is 30 mass % or more in cation ion fraction excepting O in an depth direction region having twice a thickness of an oxide film having less than 0.1 μ

m, after heating the ferritic stainless steel in an atmosphere containing 50 vol % or more of hydrogen gas and a balance substantively composed of nitrogen gas at a temperature of 800 to 1000°

C. within 10 minutes or less and cooling thereof to room temperature.

7. The ferritic stainless steel for a fuel cell according to claim 5, wherein, a maximal concentration of Ti in a surface of the ferritic stainless steel is 3 mass % or more in cation ion fraction excepting O.

8. The ferritic stainless steel for a fuel cell according to claim 5, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, Sn;

1% or less, Sb;

1% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, Ga;

0.1% or less, Mg;

0.01% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

20. The ferritic stainless steel for a fuel cell according to claim 7, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, Sn;

1% or less, Sb;

1% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, Ga;

0.1% or less, Mg;

0.01% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

6. A ferritic stainless steel for a fuel cell comprising, in mass %, Cr:

11 to 25%, C;

0.03% or less, Si;

2% or less, Mn;

2% or less, Al;

0.5 to 4.0%, P;

0.05% or less, S;

0.01% or less, N;

0.03% or less, Ti;

1% or less, and a balance composed of Fe and unavoidable impurities, wherein,

a maximal concentration of Al in a surface of the ferritic stainless steel is 30 mass % or more in cation ion fraction excepting O in an depth direction region having twice a thickness of an oxide film having less than 0.1 μ

m, after heating the ferritic stainless steel in an atmosphere of air at a temperature of 850°

C. for 100 hours and cooling thereof to room temperature.

18. The ferritic stainless steel for a fuel cell according to claim 6, wherein, a maximal concentration of Ti in a surface of the ferritic stainless steel is 3 mass % or more in cation ion fraction excepting O.

19. The ferritic stainless steel for a fuel cell according to claim 6, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, Sn;

1% or less, Sb;

1% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, Ga;

0.1% or less, Mg;

0.01% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

21. The ferritic stainless steel for a fuel cell according to claim 18, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, Sn;

1% or less, Sb;

1% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, Ga;

0.1% or less, Mg;

0.01% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

9. A ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell comprising, in mass %, Cr:

11 to 25%, C;

0.03% or less, Si;

2% or less, Mn;

2% or less, Al;

0.5 to 4.0%, P;

0.05% or less, S;

0.01% or less, N;

0.03% or less, Ti;

0.5% or less, and a balance composed of Fe and unavoidable impurities, wherein,

the ferritic stainless steel further comprises one or two or more of elements selected from a group consisting of Ga;

0.1% or less, Mg;

0.01% or less and Zn;

0.05% or less,

a total amount Ga+Mg+Zn satisfies Ga+Mg+Zn>

0.001%, and

a balance is composed of Fe and unavoidable impurities.

10. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 9, further comprising, in mass %, one or two of elements selected from a group consisting of Sn:

1.0% or less, and Sb;

1.0% or less.

11. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 9, wherein, the ferritic stainless steel includes in mass %, Si:

0.3% or more, Al;

1.5% or more, and Ti;

0.1% or more.

12. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 9, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

13. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 9, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

22. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 10, wherein, the ferritic stainless steel includes in mass %, Si:

0.3% or more, Al;

1.5% or more, and Ti;

0.1% or more.

23. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 10, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

24. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 11, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

25. The ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell according to claim 22, further comprising, in mass %, one or two or more of elements selected from a group consisting of Ni:

1% or less, Cu;

1% or less, Mo;

2% or less, W;

1% or less, Co;

0.5% or less, Nb;

0.5% or less, V;

0.5% or less, Zr;

0.5% or less, B;

0.005% or less, Ca;

0.005% or less, La;

0.1% or less, Y;

0.1% or less, Hf;

0.1% or less, and REM;

0.1% or less.

26. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 10, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

27. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 11, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

28. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 12, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

29. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 22, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

30. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 23, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

31. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 24, in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.

32. A method for producing the ferritic stainless steel having advantages of a resistance to Cr vaporizing for a fuel cell, the method comprising:

a heating step of heating the ferritic stainless steel having a composition of the ferritic stainless steel according to claim 25 in an atmosphere containing oxygen or hydrogen at a temperature of 700 to 1100°

C., to form an oxide film on a surface of the ferritic stainless steel.