FERRITIC STAINLESS STEEL MATERIAL FOR BRAZING AND HEAT EXCHANGER MEMBER

• US 20120085513A1
• Filed: 06/14/2010
• Published: 04/12/2012
• Est. Priority Date: 06/15/2009
• Status: Active Grant

• Current Assignee: Nippon Steel Stainless Steel Corporation (Nippon Steel Corporation)
• Original Assignee: Nisshin Steel Company Limited (Nippon Steel Corporation)
• Inventors: Oku, Manabu, Nakamura, Sadayuki, Hori, Yoshiaki
• Granted Patent: US 9,932,650 B2
• Time in Patent Office: Days
• US Class Current: 165/51
• CPC Class Codes: B23K 2101/14 Heat exchangers
• CPC Class Codes: B23K 35/308 with Cr as next major constituent
• CPC Class Codes: C21D 6/002 containing Cr C21D6/004 takes precedence
• CPC Class Codes: C21D 8/0273 Final recrystallisation annealing
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/20 with copper
• CPC Class Codes: C22C 38/26 with niobium or tantalum
• CPC Class Codes: F28D 21/0003 the heat being recuperated from exhaust gases F28D21/0014 takes precedence
• CPC Class Codes: F28D 7/16 the conduits being arranged in parallel spaced relation F28D7/0008 - F28D7/0058 take precedence; F28D7/02 - F28D7/10 take precedence
• CPC Class Codes: F28F 1/12 the means being only outside the tubular element
• CPC Class Codes: F28F 21/083 from stainless steel
• CPC Class Codes: F28F 21/089 Coatings, claddings or bonding layers made from metals or metal alloys F28F19/06 takes precedence

Abstract

A ferritic stainless steel material for brazing without grain coarsening has a partially recrystallized structure and composition comprising, in % by mass, C:0.03% or less, Si: more than 0.1 to 3%, Mn: 0.1 to 2%, Cr: 10 to 35%, Nb: 0.2 to 0.8%, N: 0.03% or less, if necessary, at least one of Mo, Cu, V and W: 4% or less in total, at least one of Ti and Zr: 0.5% or less in total, at least one of Ni and Co: 5% or less in total, or at least one of Al: 6% or less, REM (rare earth metal): 0.2% or less and Ca: 0.1% or less, the remainder being Fe and unavoidable impurities, wherein area ratio in percentage of recrystallized grains formed by heating after cold working is from 10 to 80%.

Claims

1. A ferritic stainless steel material for brazing, having partially recrystallized structure and a chemical composition comprising, in % by mass, C:

0.03% or less, Si;

more than 0.1 to 3%, Mn;

0.1 to 2%, Cr;

10 to 35%, Nb;

0.2 to 0.8%, N;

0.03% or less, and the remainder being Fe and unavoidable impurities, wherein area ratio in percent of recrystallized grains formed by heating after cold working is from 10 to 80%.

2. The ferritic stainless steel material according to claim 1, having the chemical composition further containing at least one of Mo, Cu, V and W in the total amount of 4% or less.

3. The ferritic stainless steel material according to claim 1, having the chemical composition further containing at least one of Ti and Zr in the total amount of 0.5% or less.

4. The ferritic stainless steel material according to claim 1, having the chemical composition further containing at least one of Ni and Co in the total amount of 5% or less

5. The ferritic stainless steel material according to claim 1, having the chemical composition further containing at least one of Al:

6% or less, REM (rare earth metal);

0.2% or less and Ca;

0.1% or less.

6. The ferritic stainless steel material according to claim 1, wherein the total content of C and N is 0.01% or more.

7. A heat exchanger member comprising the ferritic stainless steel material according to claim 1, brazed using any one of nickel brazing filler defined in JIS Z3265, nickel brazing filler containing Ni in an amount of 35% by mass or more, copper brazing filler or copper alloy brazing filler, defined in JIS Z3262, and iron brazing filler, wherein ferrite crystal grains of the steel do not penetrate the thickness of the steel and have an average crystal grain size of 500 μ

m or less.

8. The heat exchanger member according to claim 7, which is EGR cooler of automobiles, obtained by brazing the steel material using nickel brazing filler defined in JIS Z3265 or nickel brazing filler containing Ni in an amount of 35% by mass or more.