Steel plate and method for manufacturing the same

Abstract

An object is to provide a steel plate having excellent deformability in the central portion in the thickness direction and a method for manufacturing the steel plate. A steel plate having a chemical composition containing, by mass %, C: 0.01% to 0.15%, Si: 0.01% to 1.00%, Mn: 0.10% to 2.00%, P: 0.010% or less, S: 0.0050% or less, Al: 0.002% to 0.100%, Ni: 5.0% to 10.0%, N: 0.0010% to 0.0080%, and with a balance being Fe and incidental impurities and a percentage reduction of area of 30% or more in a tensile test in the thickness direction performed on the central portion in the thickness direction.

1 . A steel plate having a chemical composition comprising, by mass %:
 C: 0.01% to 0.15%,   Si: 0.01% to 1.00%,   Mn: 0.10% to 2.00%,   P: 0.010% or less,   S: 0.0050% or less,   Al: 0.002% to 0.100%,   Ni: 5.0% to 10.0%,   N: 0.0010% to 0.0080%, and   a balance being Fe and incidental impurities,   wherein when a test specimen of the steel plate is subjected to a tensile test along a thickness direction of the test specimen, a percentage reduction of an area of the test specimen is 30% or more.   
     
     
         2 . The steel plate according to  claim 1 , wherein the chemical composition further comprises, by mass %, at least one group selected from the group consisting of Group A and Group B:
 Group A: at least one selected from the group consisting of:
 Cr: 0.01% to 1.50%, 
 Mo: 0.03% to 1.0%, 
 Nb: 0.001% to 0.030%, 
 V: 0.01% to 0.10%, 
 Ti: 0.003% to 0.050%, 
 B: 0.0003% to 0.0100%, and 
 Cu: 0.01% to 1.00%, and 
   Group B: at least one selected from the group consisting of:
 Sn: 0.01% to 0.30%, 
 Sb: 0.01% to 0.30%, 
 W: more than 0% to 2.00%, 
 Co: more than 0% to 2.00%, 
 Ca: 0.0005% to 0.0050%, 
 Mg: 0.0005% to 0.0050%, 
 Zr: 0.0005% to 0.0050%, and 
 REM: 0.0010% to 0.0100%. 
   
     
     
         3 . (canceled) 
     
     
         4 . A method for manufacturing the steel plate according to  claim 1 , the method comprising
 heating a slab having the chemical composition to a temperature that is in a range of 1000° C. or higher and 1300° C. or lower and   hot rolling the heated slab, including finish rolling at a reduction ratio of 3 or more and, and performing that each at least two rolling passes of final three rolling passes at a rolling shape factor of 0.7 or more.   
     
     
         5 . A method for manufacturing the steel plate according to  claim 2 , the method comprising
 heating a slab having the chemical composition to a temperature that is in a range of 1000° C. or higher and 1300° C. or lower and   hot rolling the heated slab, including finish rolling at a reduction ratio of 3 or more, and performing at least two rolling passes of final three rolling passes at a rolling shape factor of 0.7 or more.