Ferritic stainless steel and production method therefor

Abstract

Provided are a ferritic stainless steel and a method for producing the ferritic stainless steel. A ferritic stainless steel of the present invention contains, in terms of % by mass, C: 0.005% to 0.05%, Si: 0.02% to 0.50%, Mn: 0.05% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06%, V: 0.01% to 0.25%, Ti: 0.001% to 0.020%, Nb: 0.001% to 0.030%, and the balance being Fe and unavoidable impurities, in which V/(Ti+Nb)≧2.0 is satisfied.

1 . A ferritic stainless steel comprising, in terms of % by mass, C: 0.005% to 0.05%, Si: 0.02% to 0.50%, Mn: 0.05% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06%, V: 0.01% to 0.25%, Ti: 0.001% to 0.020%, Nb: 0.001% to 0.030%, and the balance being Fe and unavoidable impurities, wherein V/(Ti+Nb)≧2.0 is satisfied. 
     
     
         2 . A ferritic stainless steel comprising, in terms of % by mass, C: 0.01% to 0.05%, Si: 0.02% to 0.50%, Mn: 0.2% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 16.0% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06%, V: 0.01% to 0.25%, Ti: 0.001% to 0.015%, Nb: 0.001% to 0.025%, and the balance being Fe and unavoidable impurities, wherein V/(Ti+Nb)≧2.0 is satisfied. 
     
     
         3 . The ferritic stainless steel according to  claim 1 , further comprising, in terms of % by mass, at least one selected from Cu: 0.1% to 1.0%, Ni: 0.1% to 1.0%, Mo: 0.1% to 0.5%, and Co: 0.01% to 0.5%. 
     
     
         4 . The ferritic stainless steel according to  claim 2 , further comprising, in terms of % by mass, at least one selected from Cu: 0.1% to 1.0%, Ni: 0.1% to 1.0%, Mo: 0.1% to 0.5%, and Co: 0.01% to 0.5%. 
     
     
         5 . The ferritic stainless steel according to  claim 1 , further comprising, in terms of % by mass, at least one selected from Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, REM: 0.01% to 0.10%, and Ca: 0.0002% to 0.0020%. 
     
     
         6 . The ferritic stainless steel according to  claim 2 , further comprising, in terms of % by mass, at least one selected from Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, REM: 0.01% to 0.10%, and Ca: 0.0002% to 0.0020%. 
     
     
         7 . The ferritic stainless steel according to  claim 3 , further comprising, in terms of % by mass, at least one selected from Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, REM: 0.01% to 0.10%, and Ca: 0.0002% to 0.0020%. 
     
     
         8 . The ferritic stainless steel according to  claim 4 , further comprising, in terms of % by mass, at least one selected from Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, REM: 0.01% to 0.10%, and Ca: 0.0002% to 0.0020%. 
     
     
         9 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 1 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         10 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 2 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         11 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 3 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         12 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 4 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         13 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 5 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         14 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 6 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         15 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 7 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes. 
     
     
         16 . A method for producing a ferritic stainless steel, comprising hot-rolling a steel slab having the composition described in  claim 8 , annealing the resulting hot rolled sheet by holding the hot rolled sheet in a temperature range of 880° C. to 1000° C. for 5 seconds to 15 minutes to obtain a hot-rolled and annealed sheet, cold-rolling the hot-rolled and annealed sheet, and annealing the resulting cold-rolled sheet by holding the cold-rolled sheet in a temperature range of 800° C. to 950° C. for 5 seconds to 5 minutes.