Ferritic stainless steel sheet excellent in formability and method for production thereof

Abstract

The present invention provides a ferritic stainless steel sheet superior in shapeability containing, by wt %, C: 0.001 to 0.010%, Si: 0.01 to 1.0%, Mn: 0.01 to 1.0%, P: 0.01 to 0.04%, Cr: 10 to 20%, N: 0.001 to 0.020%, Nb: 0.3 to 1.0%, and Mo: 0.5 to 2.0%, wherein the total precipitates are, by wt %, 0.05 to 0.60%. A method of production of a ferritic stainless steel sheet superior in shapeability comprising producing a cold rolling material in the production process so that the Nb-based precipitates become, by vol %, 0.15% to 0.6% and have a diameter of 0.1 μm to 1 μm and/or so that the recrystallized grain size becomes 1 μm to 40 μm and the recrystallization rate becomes 10 to 90%, then cold rolling and annealing it at 1010 to 1080° C.

1 . A ferritic stainless steel sheet superior in shapeability containing, by wt %, C: 0.001 to 0.010%, Si: 0.01 to 0.3%, Mn: 0.01 to 0.3%, P: 0.01 to 0.04%, N: 0.001 to 0.020%, Cr: 10 to 20%, Nb: 0.3 to 1.0%, and Mo: 0.5 to 2.0% and having a balance of Fe and unavoidable impurities, said ferritic stainless steel characterized in that the total precipitates are, by wt %, 0.05 to 0.60%.  
   
   
       2 . A ferritic stainless steel sheet superior in shapeability as set forth in  claim 1 , characterized by further containing, by wt %, one or more of Ti: 0.05 to 0.20%, Al: 0.005 to 0.100%, and B: 0.0003 to 0.0050%.  
   
   
       3 . A ferritic stainless steel sheet superior in shapeability as set forth in  claim 1 , characterized by further containing, by wt %, one or more of Cu: 0.2 to 3.0%, W: 0.01 to 1.0%, and Sn: 0.01 to 1.0%.  
   
   
       4 . A method of production of a ferritic stainless steel sheet superior in shapeability characterized by producing a cold rolling material having a composition as set forth in  claim 1  so that the Nb-based precipitates become, by vol %, 0.15% to 0.6% and have a diameter of 0.1 μm to 1 μm, then cold rolling and annealing it at 1010 to 1080° C.  
   
   
       5 . A method of production of a ferritic stainless steel sheet superior in shapeability characterized by producing a cooled rolling material having a composition as set forth in  claim 1  so that the recrystallized grain size becomes 1 μm to 40 μm and the recrystallization rate becomes 10 to 90%, then cold rolling and annealing it at 1010 to 1080° C.  
   
   
       6 . A method of production of a ferritic stainless steel sheet superior in shapeability characterized by producing a cold rolling material having a composition as set forth in  claim 1  so that the Nb-based precipitates become, by vol %, 0.15% to 0.6% and have a diameter of 0.1 μm to 1 μm and so that the recrystallized grain size becomes 1 μm to 40 μm and the recrystallization rate becomes 10 to 90%, then cold rolling and annealing it at 1010 to 1080° C.