Ferritic stainless steel

Abstract

A ferritic stainless steel that generates only a small amount of black spots in weld zone, the steel containing, in mass %, 0.020% or less of C, 0.025% or less of N, 1.0% or less of Si, 1.0% or less of Mn, 0.035% or less of P, 0.01% or less of S, 16.0 to 25.0% of Cr, 0.12% or less of Al, 0.05 to 0.35% of Ti, and 0.0015% or less of Ca, and the balance consisting of Fe and unavoidable impurities, wherein the following formula 1 is satisfied. BI=3Al+Ti+0.5Si+200Ca≦0.8  (1) where Al, Ti, Si, and Ca in the formula 1 each denotes an amount of each element in mass % of the steel.

1 . A ferritic stainless steel containing, in mass %, 0.020% or less of C, 0.025% or less of N, 1.0% or less of Si, 1.0% or less of Mn, 0.035% or less of P, 0.01% or less of S, 16.0 to 25.0% of Cr, 0.12% or less of Al, 0.05 to 0.35% of Ti, 0.05 to 0.6% of Nb and 0.0002 to 0.0015% of Ca, and the balance consisting of Fe and unavoidable impurities, wherein the following formula 1 is satisfied.
   BI=3Al+Ti+0.5Si+200Ca≦0.8  (1)
   
       where Al, Ti, Si, and Ca in the formula 1 each denotes an amount of each element in mass % of the steel. 
     
     
         2 . (canceled) 
     
     
         3 . A ferritic stainless steel according to  claim 1 , further containing, in mass %, 3.0% or less of Mo. 
     
     
         4 . (canceled) 
     
     
         5 . A ferritic stainless steel according to  claim 1  or  3 , further containing, in mass %, one or two selected from 2.0% or less of Cu and 2.0% or less of Ni. 
     
     
         6 . A ferritic stainless steel according to  claim 1  or  3 , further containing, in mass %, one or two selected from 0.2% or less of V and 0.2% or less of Zr. 
     
     
         7 . A ferritic stainless steel according to  claim 5 , further containing, in mass %, one or two selected from 0.2% or less of V and 0.2% or less of Zr. 
     
     
         8 . A ferritic stainless steel according to  claim 1  or  3 , further containing, in mass %, 0.005% or less of B. 
     
     
         9 . A ferritic stainless steel according to  claim 5 , further containing, in mass %, 0.005% or less of B. 
     
     
         10 . A ferritic stainless steel according to  claim 6 , further containing, in mass %, 0.005% or less of B. 
     
     
         11 . A ferritic stainless steel according to  claim 7 , further containing, in mass %, 0.005% or less of B.