Hot-rolled ferritic stainless steel sheet and method for manufacturing same

Abstract

Provided is a hot-rolled ferritic stainless steel sheet which has sufficient corrosion resistance and which can prevent the occurrence of cracking when subjected to blanking to be formed into a thick flange, and also provided is a method for manufacturing the hot-rolled ferritic stainless steel sheet. A hot-rolled ferritic stainless steel sheet having a chemical composition containing, in mass %, C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001 to 0.50%, N: 0.001 to 0.020%, Cr: 11.0 to 24.0%, Ni: 0.01 to 2.00%, and Nb: 0.12 to 0.80%, with the balance being Fe and incidental impurities, wherein the hot-rolled ferritic stainless steel sheet has a threshold stress intensity factor KIC of 25 MPa·m1/2 or more.

1 . A hot-rolled ferritic stainless steel sheet having a chemical composition comprising, in mass %,
 C: 0.001 to 0.020%,   Si: 0.05 to 1.00%,   Mn: 0.05 to 1.00%,   P: 0.04% or less,   S: 0.01% or less,   Al: 0.001 to 0.50%,   N: 0.001 to 0.020%,   Cr: 11.0 to 24.0%,   Ni: 0.01 to 2.00%, and   Nb: 0.12 to 0.80%, with a balance of Fe and incidental impurities,   wherein the hot-rolled ferritic stainless steel sheet has a threshold stress intensity factor K IC  of 25 MPa·m 1/2  or more.   
     
     
         2 . A hot-rolled ferritic stainless steel sheet having a chemical composition comprising, in mass %,
 C: 0.001 to 0.020%,   Si: 0.05 to 1.00%,   Mn: 0.05 to 1.00%,   P: 0.04% or less,   S: 0.01% or less,   Al: 0.001 to 0.50%,   N: 0.001 to 0.020%,   Cr: 13.0 to 24.0%,   Ni: 0.01 to 0.60%, and   Nb: 0.12 to 0.80%, with a balance of Fe and incidental impurities,   wherein the hot-rolled ferritic stainless steel sheet has a threshold stress intensity factor K IC  of 25 MPa·m 1/2  or more.   
     
     
         3 . The hot-rolled ferritic stainless steel sheet according to  claim 1 , wherein the chemical composition further comprises, in mass %, one or more selected from
 Cu: 0.01 to 1.50%,   Mo: 0.01 to 2.00%,   W: 0.01 to 0.20%, and   Co: 0.01 to 0.20%.   
     
     
         4 . The hot-rolled ferritic stainless steel sheet according to  claim 2 , wherein the chemical composition further comprises, in mass %, one or more selected from
 Cu: 0.01 to 1.50%,   Mo: 0.01 to 2.00%,   W: 0.01 to 0.20%, and   Co: 0.01 to 0.20%.   
     
     
         5 . The hot-rolled ferritic stainless steel sheet according to  claim 1 , wherein the chemical composition further comprises, in mass %, one or more selected from
 Ti: 0.01 to 0.30%,   V: 0.01 to 0.20%,   Zr: 0.01 to 0.20%,   REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0005 to 0.0030%.   
     
     
         6 . The hot-rolled ferritic stainless steel sheet according to  claim 2 , wherein the chemical composition further comprises, in mass %, one or more selected from
 Ti: 0.01 to 0.30%,   V: 0.01 to 0.20%,   Zr: 0.01 to 0.20%,   REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0005 to 0.0030%.   
     
     
         7 . The hot-rolled ferritic stainless steel sheet according to  claim 3 , wherein the chemical composition further comprises, in mass %, one or more selected from
 Ti: 0.01 to 0.30%,   V: 0.01 to 0.20%,   Zr: 0.01 to 0.20%,   REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0005 to 0.0030%.   
     
     
         8 . The hot-rolled ferritic stainless steel sheet according to  claim 4 , wherein the chemical composition further comprises, in mass %, one or more selected from
 Ti: 0.01 to 0.30%,   V: 0.01 to 0.20%,   Zr: 0.01 to 0.20%,   REM: 0.001 to 0.100%,   B: 0.0002 to 0.0025%,   Mg: 0.0005 to 0.0030%, and   Ca: 0.0005 to 0.0030%.   
     
     
         9 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 1 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         10 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 2 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         11 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 3 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         12 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 4 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         13 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 5 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         14 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 6 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         15 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 7 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.   
     
     
         16 . A method for manufacturing the hot-rolled ferritic stainless steel sheet according to  claim 8 , the method comprising hot rolling, the hot rolling including performing finish rolling including three or more passes,
 wherein a temperature range for final three passes of the finish rolling is 800 to 1100° C., and an accumulated rolling reduction ratio for the final three passes is 25% or more.