Ferritic stainless steel sheet for water heater excellent in corrosion resistance at welded part and steel sheet toughness

• US 8,383,034 B2
• Filed: 01/07/2008
• Issued: 02/26/2013
• Est. Priority Date: 01/12/2007
• Status: Active Grant

• Current Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Original Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Inventors: Fukuda, Kunio, Funakawa, Yoshimasa, Okada, Shuji, Kasamo, Toshihiro, Kobori, Katsuhiro, Ujiro, Takumi, Ishii, Tomohiro
• Primary Examiner(s): Yee, Deborah
• Application Number:
  US12/516,212
• Publication Number:
  US 20100061878A1
• Time in Patent Office: 1,877 Days
• Field of Search: 148/325, 420/61, 420/63, 420/68, 420/69
• US Class Current: 420/68
• CPC Class Codes: C21D 2211/001 Austenite
• CPC Class Codes: C21D 6/002 containing Cr C21D6/004 takes precedence
• CPC Class Codes: C21D 8/0226 Hot rolling
• CPC Class Codes: C21D 8/0236 Cold rolling
• CPC Class Codes: C21D 8/0273 Final recrystallisation annealing
• CPC Class Codes: C21D 9/46 for sheet metals
• 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 38/06 containing aluminium
• CPC Class Codes: C22C 38/22 with molybdenum or tungsten
• CPC Class Codes: C22C 38/26 with niobium or tantalum
• CPC Class Codes: C22C 38/44 with molybdenum or tungsten
• CPC Class Codes: C22C 38/46 with vanadium
• CPC Class Codes: C22C 38/48 with niobium or tantalum
• CPC Class Codes: C22C 38/50 with titanium or zirconium

Abstract

A ferritic stainless steel sheet for a water heater with excellent corrosion resistance of welds and toughness includes, in terms of mass %, 0.020% or less of C, 0.30 to 1.00% of Si, 1.00% or less of Mn, 0.040% or less of P, 0.010% or less of S, 20.0 to 28.0% of Cr, 0.6% or less of Ni, 0.03 to 0.15% of Al, 0.020% or less of N, 0.0020 to 0.0150% of O, 0.3 to 1.5% of Mo, 0.25 to 0.60% of Nb, and 0.05% or less of Ti, the remainder being composed of Fe and unavoidable impurities, and the ferritic stainless steel sheet satisfying the following formulae (1) and (2):
25≦Cr+3.3Mo≦30  (1)
0.35≦Si+Al≦0.85  (2)
wherein Cr, Mo, Si, and Al represent the content (mass %) of Cr, Mo, Si, and Al, respectively.

Claims

1. A ferritic stainless steel sheet for a water heater comprising, in terms of mass %, 0.020% or less of C, 0.30 to 0.82% of Si, 1.00% or less of Mn, 0.040% or less of P, 0.010% or less of S, 20.0 to 28.0% of Cr, 0.1 to 0.6% of Ni, 0.03 to 0.15% of Al, 0.020% or less of N, 0.0020 to 0.0150% of O, 0.3 to 1.5% of Mo, 0.25 to 0.60% of Nb, and 0.03% or less of Ti where Ti is present, the remainder being composed of Fe and unavoidable impurities, and the ferritic stainless steel sheet satisfying the following formulae (1) and (2):

25≦

Cr+3.3Mo≦

30 

 

(1)

0.35≦

Si+Al≦

0.85  

 

(2)

wherein Cr, Mo, Si, and Al represent the contents (mass %) of Cr, Mo, Si, and Al, respectively.

2. The ferritic stainless steel sheet of claim 1, further comprising in terms of mass %, 0.005 to 0.50% of V, more than 22% to 28.0% of Cr, and satisfies the following formula (3):

0.1≦

4V/(Nb−

8(C+N))≦

5.0 

 

(3)

wherein V, Nb, C, N represent the contents (mass %) of V, Nb, C, and N, respectively.

3. The ferritic stainless steel sheet of claim 1 or 2, further comprising in terms of mass %, 0.2 to 1.0% of Cu and/or 0.10 to 0.60% of Zr.