Ferritic stainless steel sheet and method for manufacturing the same

Abstract

The present invention provides a ferritic stainless steel sheet and a method for manufacturing the same. A ferritic stainless steel sheet has a composition containing C: 0.001 to 0.020%, Si: 0.05 to 0.35%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001 to 0.300%, Cr: 10.0 to 13.0%, Ni: 0.75 to 1.50%, Ti: 0.05 to 0.35%, and N: 0.001 to 0.020%, with the balance being Fe and inevitable impurities, in which γI [AD] represented by formula (1) below is 65% or more, and a metal structure has an average crystal grain size of 45 μm or less: γI [%]=24Ni+12Mn+6Cu−18Si−12Cr−12Mo+188 (1), where Ni, Mn, Cu, Si, Cr, and Mo represent contents of the respective elements (percent by mass), and an element not contained represents 0.

1 . A ferritic stainless steel sheet having a composition containing, in percent by mass,
 C: 0.001 to 0.020%,   Si: 0.05 to 0.35%,   Mn: 0.05 to 1.00%,   P: 0.04% or less,   S: 0.01% or less,   Al: 0.001 to 0.300%,   Cr: 10.0 to 13.0%,   Ni: 0.75 to 1.50%,   Ti: 0.05 to 0.35%, and   N: 0.001 to 0.020%, with the balance being Fe and inevitable impurities,   wherein γ I  [%] represented by formula (1) below is 65% or more, and a metal structure has an average crystal grain size of 45 μm or less:   γ I  [%]=24Ni+12Mn+6Cu−18Si−12Cr−12Mo+188 (1), where Ni, Mn, Cu, Si, Cr, and Mo represent contents of the respective elements (percent by mass), and an element not contained represents 0.   
     
     
         2 . The ferritic stainless steel sheet according to  claim 1 , wherein the composition further contains, in percent by mass, one or two or more selected from
 Cu: 0.01 to 1.00%,   Mo: 0.01 to 1.00%,   W: 0.01 to 0.20%, and   Co: 0.01 to 0.20%.   
     
     
         3 . The ferritic stainless steel sheet according to  claim 1 , wherein the composition further contains, in percent by mass, one or two or more selected from
 V: 0.01 to 0.20%,   Nb: 0.01 to 0.10%, and   Zr: 0.01 to 0.20%.   
     
     
         4 . The ferritic stainless steel sheet according to  claim 2 , wherein the composition further contains, in percent by mass, one or two or more selected from
 V: 0.01 to 0.20%,   Nb: 0.01 to 0.10%, and   Zr: 0.01 to 0.20%.   
     
     
         5 . The ferritic stainless steel sheet according to  claim 1 , wherein the composition further contains, in percent by mass, one or two or more selected from
 REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0003 to 0.0030%.   
     
     
         6 . The ferritic stainless steel sheet according to  claim 2 , wherein the composition further contains, in percent by mass, one or two or more selected from
 REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0003 to 0.0030%.   
     
     
         7 . The ferritic stainless steel sheet according to  claim 3 , wherein the composition further contains, in percent by mass, one or two or more selected from
 REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0003 to 0.0030%.   
     
     
         8 . The ferritic stainless steel sheet according to  claim 4 , wherein the composition further contains, in percent by mass, one or two or more selected from
 REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0003 to 0.0030%.   
     
     
         9 . A method for manufacturing the ferritic stainless steel sheet according to  claim 1 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         10 . A method for manufacturing the ferritic stainless steel sheet according to  claim 2 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         11 . A method for manufacturing the ferritic stainless steel sheet according to  claim 3 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         12 . A method for manufacturing the ferritic stainless steel sheet according to  claim 4 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         13 . A method for manufacturing the ferritic stainless steel sheet according to  claim 5 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         14 . A method for manufacturing the ferritic stainless steel sheet according to  claim 6 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         15 . A method for manufacturing the ferritic stainless steel sheet according to  claim 7 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.   
     
     
         16 . A method for manufacturing the ferritic stainless steel sheet according to  claim 8 , comprising:
 a hot rolling process in which a steel slab having the composition is heated at 1,050 to 1,250° C., and then subjected to hot rolling; and   a hot-rolled sheet annealing process in which a hot-rolled steel sheet obtained in the hot rolling process is subjected to hot-rolled sheet annealing at 750 to 1,050° C.