Hot-rolled steel sheet

Abstract

This hot-rolled steel sheet has a predetermined chemical composition and a microstructure, in which, in a texture of a surface layer region, pole densities of {001}<110>, {111}<110>, and {112}<110> orientation groups are 2.0 or more, in a texture of an internal region, a pole density of a {110}<112> orientation is 5.0 or less, and a tensile strength is 1,180 MPa or more.

1 . A hot-rolled steel sheet comprising, as a chemical composition, by mass %:
 C: 0.100% to 0.500%;   Si: 0.100% to 3.000%;   Mn: 0.50% to 3.00%;   P: 0.100% or less;   S: 0.0100% or less;   Al: 1.000% or less;   N: 0.0100% or less;   Ti: 0% to 0.20%;   Nb: 0% to 0.100%;   Ca: 0% to 0.0060%;   Mo: 0% to 0.50%;   Cr: 0% to 1.00%;   V: 0% to 0.50%;   Cu: 0% to 0.50%;   Ni: 0% to 0.50%;   Sn: 0% to 0.050%; and   a remainder comprising Fe and impurities,   wherein a microstructure in a region from a depth of ⅛ of a sheet thickness from a surface to a depth of ⅜ of the sheet thickness from the surface includes, by area %,
 90% to 100% of martensite, and 
 0% to 10% of a remainder in microstructure, 
   in a texture of a region from the surface to the depth of ⅛ of the sheet thickness from the surface,
 pole densities of {001}<110>, {111}<110>, and {112}<110> orientation groups are 2.0 or more, 
   in a texture of a region from the depth of ⅛ of the sheet thickness from the surface to a depth of ½ of the sheet thickness from the surface,
 a pole density of a {110}<112> orientation is 5.0 or less, and 
   a tensile strength of the hot-rolled steel sheet is 1,180 MPa or more.   
     
     
         2 . The hot-rolled steel sheet according to  claim 1 , wherein the chemical composition comprises, by mass %, one or more of:
 Ti: 0.02% to 0.20%,   Nb: 0.010% to 0.100%,   Ca: 0.0001% to 0.0060%,   Mo: 0.01% to 0.50%,   Cr: 0.01% to 1.00%,   V: 0.01% to 0.50%,   Cu: 0.01% to 0.50%,   Ni: 0.01% to 0.50%, and   Sn: 0.001% to 0.050%.