Dual phase stainless steel sheet and dual phase stainless hot-rolled sheet, and method for manufacturing dual phase stainless steel sheet

Abstract

This titanium material is a dual phase stainless steel sheet containing an austenite and a ferrite and has a predetermined chemical composition, wherein, in a center part in a sheet thickness of a cross section in a perpendicular-to-rolling direction which is a direction perpendicular to a rolling direction on a rolled surface and a direction parallel to a sheet thickness direction, an area ratio S<001>/S<111> which is a ratio of an area proportion S<001> of a texture of a ferrite with the <001> direction oriented in the perpendicular-to-rolling direction to an area proportion S<111> of a texture of a ferrite with the <111> direction oriented in the perpendicular-to-rolling direction is 0.90 to 1.10.

1 .- 9 . (canceled) 
     
     
         10 . A dual phase stainless steel sheet containing an austenite and a ferrite,
 wherein the dual phase stainless steel sheet comprises:   
       in mass %, 
       C: 0.080% or less, 
       Si: 1.00% or less, 
       Mn: 4.00% or less, 
       P: 0.040% or less, 
       S: 0.0300% or less, 
       Ni: 1.50 to 8.00%, 
       Cr: 18.00 to 28.00%, 
       Mo: 5.00% or less, 
       Cu: 0.05 to 1.50%, and, 
       N: 0.080 to 0.320%, with the remainder of Fe and impurities,
 wherein, in a center part in a sheet thickness of a cross section in a perpendicular-to-rolling direction which is a direction perpendicular to a rolling direction on a rolled surface and a direction parallel to a sheet thickness direction, an area ratio S <001> /S <111>  which is a ratio of an area proportion S <001>  of a texture of a ferrite with the <001> direction oriented in the perpendicular-to-rolling direction to an area proportion S <111>  of a texture of a ferrite with the <111> direction oriented in the perpendicular-to-rolling direction is 0.90 to 1.10. 
 
     
     
         11 . The dual phase stainless steel sheet according to  claim 10 ,
 wherein the surface waviness height in the rolling direction is 0.3 μm or less.   
     
     
         12 . The dual phase stainless steel sheet according to  claim 10 , comprising,
 in mass %,   C: 0.030% or less,   Si: 0.75% or less,   Mn: 2.00 to 4.00%,   P: 0.040% or less,   S: 0.0200% or less,   Ni: 1.50 to 2.50%,   Cr: 18.00 to 21.50%,   Mo: 0.60% or less,   Cu: 0.50 to 1.50%, and,   N: 0.150 to 0.200%, with the remainder of Fe and impurities.   
     
     
         13 . The dual phase stainless steel sheet according to  claim 11 , comprising,
 in mass %,   C: 0.030% or less,   Si: 0.75% or less,   Mn: 2.00 to 4.00%,   P: 0.040% or less,   S: 0.0200% or less,   Ni: 1.50 to 2.50%,   Cr: 18.00 to 21.50%,   Mo: 0.60% or less,   Cu: 0.50 to 1.50%, and,   N: 0.150 to 0.200%, with the remainder of Fe and impurities.   
     
     
         14 . The dual phase stainless steel sheet according to  claim 10  comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%, 
 O: 0.0070% or less, 
 Nb: 0.005 to 0.20%, 
 Ti: 0.005 to 0.20%, 
 Co: 0.005 to 0.25%, 
 V: 0.005 to 0.15%, 
 Sn: 0.005 to 0.20%, 
 Sb: 0.005 to 0.20%, 
 Ga: 0.001 to 0.050%, 
 Zr: 0.005 to 0.50%, 
 Ta: 0.005 to 0.100%, and, 
 B: 0.0002 to 0.0050%. 
 
     
     
         15 . The dual phase stainless steel sheet according to  claim 11 , comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%,   0.0070% or less,   Nb: 0.005 to 0.20%,   Ti: 0.005 to 0.20%,   Co: 0.005 to 0.25%,   V: 0.005 to 0.15%,   Sn: 0.005 to 0.20%,   Sb: 0.005 to 0.20%,   Ga: 0.001 to 0.050%,   Zr: 0.005 to 0.50%,   Ta: 0.005 to 0.100%, and,   B: 0.0002 to 0.0050%.   
     
     
         16 . The dual phase stainless steel sheet according to  claim 12 , comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%,   O: 0.0070% or less,   Nb: 0.005 to 0.20%,   Ti: 0.005 to 0.20%,   Co: 0.005 to 0.25%,   V: 0.005 to 0.15%,   Sn: 0.005 to 0.20%,   Sb: 0.005 to 0.20%,   Ga: 0.001 to 0.050%,   Zr: 0.005 to 0.50%,   Ta: 0.005 to 0.100%, and,   B: 0.0002 to 0.0050%.   
     
     
         17 . The dual phase stainless steel sheet according to  claim 13 , comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%,   O: 0.0070% or less,   Nb: 0.005 to 0.20%,   Ti: 0.005 to 0.20%,   Co: 0.005 to 0.25%,   V: 0.005 to 0.15%,   Sn: 0.005 to 0.20%,   Sb: 0.005 to 0.20%,   Ga: 0.001 to 0.050%,   Zr: 0.005 to 0.50%,   Ta: 0.005 to 0.100%, and,   B: 0.0002 to 0.0050%.   
     
     
         18 . A dual phase stainless hot-rolled sheet containing an austenite and a ferrite,
 wherein the dual phase stainless hot-rolled sheet comprises:   
       in mass %, 
       C: 0.080% or less, 
       Si: 1.00% or less, 
       Mn: 4.00% or less, 
       P: 0.040% or less, 
       S: 0.0300% or less, 
       Ni: 1.50 to 8.00%, 
       Cr: 18.00 to 28.00%, 
       Mo: 5.00% or less, 
       Cu: 0.05 to 1.50%, and, 
       N: 0.080 to 0.320%, with the remainder of Fe and impurities
 wherein the difference between the Vickers hardness of the austenite and the Vickers hardness of the ferrite is 50 HV or more and 75 HV or less. 
 
     
     
         19 . The dual phase stainless hot-rolled sheet according to  claim 18 , comprising, in mass %, Ni: 2.00 to 8.00%. 
     
     
         20 . The dual phase stainless hot-rolled sheet according to  claim 18 , comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%,   O: 0.0070% or less,   Nb: 0.005 to 0.20%,   Ti: 0.005 to 0.20%,   Co: 0.005 to 0.25%,   V: 0.005 to 0.15%,   Sn: 0.005 to 0.20%,   Sb: 0.005 to 0.20%,   Ga: 0.001 to 0.050%,   Zr: 0.005 to 0.50%,   Ta: 0.005 to 0.100%, and,   B: 0.0002 to 0.0050%.   
     
     
         21 . The dual phase stainless hot-rolled sheet according to  claim 19 , comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%,   O: 0.0070% or less,   Nb: 0.005 to 0.20%,   Ti: 0.005 to 0.20%,   Co: 0.005 to 0.25%,   V: 0.005 to 0.15%,   Sn: 0.005 to 0.20%,   Sb: 0.005 to 0.20%,   Ga: 0.001 to 0.050%,   Zr: 0.005 to 0.50%,   Ta: 0.005 to 0.100%, and,   B: 0.0002 to 0.0050%.   
     
     
         22 . A method for manufacturing a dual phase stainless steel sheet, comprising:
 a hot rolling process in which a stainless steel containing, in mass %,   C: 0.080% or less,   Si: 1.00% or less,   Mn: 4.00% or less,   P: 0.040% or less,   S: 0.0300% or less,   Ni: 1.50 to 6.80%,   Cr: 18.00 to 28.00%,   Mo: 5.00% or less,   Cu: 0.05 to 1.50%, and   N: 0.080 to 0.320%, with the remainder of Fe and impurities is subjected to hot rolling and coiled at a temperature of 680° C. or higher;
 a heat treatment process in which the stainless steel after the hot rolling process is heated at a temperature of 500° C. or higher and lower than 600° C. and maintained for 1 hour or longer; and 
 a cold rolling process in which the stainless steel after the heat treatment process is cold-rolled. 
   
     
     
         23 . The method for manufacturing a dual phase stainless steel sheet according to  claim 22 , comprising, in mass %, in place of some Fe, one or more of
 Al: 0.003 to 0.050%,   O: 0.0070% or less,   Nb: 0.005 to 0.20%,   Ti: 0.005 to 0.20%,   Co: 0.005 to 0.25%,   V: 0.005 to 0.15%,   Sn: 0.005 to 0.20%,   Sb: 0.005 to 0.20%,   Ga: 0.001 to 0.050%,   Zr: 0.005 to 0.50%,   Ta: 0.005 to 0.100%, and,   B: 0.0002 to 0.0050%.