Ferritic stainless steel sheet for urea scr casing (as amended)

Abstract

Provided is a ferritic stainless steel sheet for a urea SCR casing which is excellent in terms of corrosion resistance in a urea SCR environment and which increases the durability of a urea SCR casing. The steel sheet has a chemical composition containing, by mass %, C: 0.020% or less, Si: 0.01% or more and 0.50% or less, Mn: 0.01% or more and 0.50% or less, P: 0.040% or less, S: 0.010% or less, Al: 0.01% or more and 0.20% or less, Cr: 20.5% or more and 24.0% or less, Cu: 0.40% or more and 0.80% or less, Ni: 0.05% or more and 0.6% or less, N: 0.020% or less, one or both selected from among Ti: 0.01% or more and 0.40% or less and Nb: 0.01% or more and 0.55% or less, and the balance being Fe and inevitable impurities, in which the relationship Ti+Nb×48/93≥8×(C+N) (in the relational expression, Ti, Nb, C, and N denote the contents (mass %) of the corresponding chemical elements) is satisfied.

1 . A ferritic stainless steel sheet for a urea SCR casing, the steel sheet having a chemical composition containing, by mass %,
 C: 0.020% or less,   Si: 0.01% or more and 0.50% or less,   Mn: 0.01% or more and 0.50% or less,   P: 0.040% or less,   S: 0.010% or less,   Al: 0.01% or more and 0.20% or less,   Cr: 20.5% or more and 24.0% or less,   Cu: 0.40% or more and 0.80% or less,   Ni: 0.05% or more and 0.6% or less,   N: 0.020% or less,   one or both selected from among Ti: 0.01% or more and 0.40% or less and Nb: 0.01% or more and 0.55% or less, and   the balance being Fe and inevitable impurities,   wherein the relationship
   Ti+Nb×48/93≥8×(C+N)   (1)
 
   is satisfied, wherein in relational expression (1), Ti, Nb, C, and N denote the contents (mass %) of the corresponding chemical elements.   
     
     
         2 . The ferritic stainless steel sheet for a urea SCR casing according to  claim 1 , the chemical composition further containing, by mass %, Mo: 0.01% or more and 0.25% or less. 
     
     
         3 . The ferritic stainless steel sheet for a urea SCR casing according to  claim 1 , the chemical composition further containing, by mass %, one, two, or all of
 V: 0.01% or more and 0.20% or less,   Zr: 0.01% or more and 0.20% or less, and   Ca: 0.0002% or more and 0.0020% or less.   
     
     
         4 . The ferritic stainless steel sheet for a urea SCR casing according to  claim 2 , the chemical composition further containing, by mass %, one, two, or all of
 V: 0.01% or more and 0.20% or less,   Zr: 0.01% or more and 0.20% or less, and   Ca: 0.0002% or more and 0.0020% or less.