Ferritic stainless steel sheet and method for manufacturing the same

Abstract

Provided are a ferritic stainless steel sheet and a method for manufacturing the steel sheet. The ferritic stainless steel sheet according to the present invention has a chemical composition containing, by mass %, C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001% to 0.10%, Cr: 15.5% to 18.0%, Ni: 0.1% to 1.0%, N: 0.005% to 0.025%, and the balance being Fe and inevitable impurities, an elongation after fracture of 28% or more, an average r-value of 0.75 or more, and a minimum value of maximum logarithmic strain at the forming limit, which is, determined on the basis of a forming limit diagram (FLD), of 0.15 or more.

1 . A ferritic stainless steel sheet having
 a chemical composition containing, by mass %, C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001% to 0.10%, Cr: 15.5% to 18.0%, Ni: 0.1% to 1.0%, N: 0.005% to 0.025%, and the balance being Fe and inevitable impurities,   an elongation after fracture of 28% or more, an average r-value of 0.75 or more, and a minimum value of maximum logarithmic strain at the forming limit, which is determined on the basis of a forming limit diagram (FLD), of 0.15 or more.   
     
     
         2 . The ferritic stainless steel sheet according to  claim 1 , the steel sheet having the chemical composition further containing, by mass %, one, two, or more selected from Cu: 0.1% to 1.0%, V: 0.01% to 0.10%, Ti: 0.001% to 0.05%, Nb: 0.001% to 0.05%, Mo: 0.1% to 0.5%, and Co: 0.01% to 0.2%. 
     
     
         3 . The ferritic stainless steel sheet according to  claim 1 , the steel sheet having the chemical composition further containing, by mass %, one, two, or more selected from Mg: 0.0002% to 0.0050%, Ca: 0.0002% to 0.0020%, B: 0.0002% to 0.0050%, and REM: 0.01% to 0.10%. 
     
     
         4 . The ferritic stainless steel sheet according to  claim 2 , the steel sheet having the chemical composition further containing, by mass %, one, two or more selected from Mg: 0.0002% to 0.0050% Ca: 0.0002% to 0.0020%, B: 0.0002% to 0.0050%, and REM: 0.01% to 0.10%. 
     
     
         5 . A method for manufacturing the ferritic stainless steel sheet according to  claim 1 , the method comprising performing hot rolling on a steel slab, performing annealing in which the hot-rolled steel sheet is held in a temperature range of 900° C. to 1100° C. for 5 seconds to 15 minutes, subsequently performing cold rolling, and performing annealing in which the cold-rolled steel sheet is held in a temperature range of 800° C. to 900° C. for 5 seconds to 5 minutes. 
     
     
         6 . A method for manufacturing the ferritic stainless steel sheet according to  claim 2 , the method comprising performing hot rolling on a steel slab, performing annealing in which the hot-rolled steel sheet is held in a temperature range of 900° C. to 1100° C. for 5 seconds to 15 minutes, subsequently performing cold rolling, and performing annealing in which the cold-rolled steel sheet is held in a temperature range of 800° C. to 900° C. for 5 seconds to 5 minutes. 
     
     
         7 . A method for manufacturing the ferritic stainless steel sheet according to  claim 3 , the method comprising performing hot rolling on a steel slab, performing annealing in which the hot-rolled steel sheet is held in a temperature range of 900° C. to 1100° C. for 5 seconds to 15 minutes, subsequently performing cold rolling, and performing annealing in which the cold-rolled steel sheet is held in a temperature range of 800° C. to 900° C. for 5 seconds to 5 minutes. 
     
     
         8 . A method for manufacturing the ferritic stainless steel sheet according to  claim 4 , the method comprising performing hot rolling on a steel slab, performing annealing in which the hot-rolled steel sheet is held in a temperature range of 900° C. to 1100° C. for 5 seconds to 15 minutes, subsequently performing cold rolling, and performing annealing in which the cold-rolled steel sheet is held in a temperature range of 800° C. to 900° C. for 5 seconds to 5 minutes.