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 region from a 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 to 8.0, 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 2.0 to 4.0, and a tensile strength is 980 MPa or more.

1 . A hot-rolled steel sheet comprising, as a chemical composition, by mass %:
 C: 0.100% to 0.350%;   Si: 0.010% to 3.00%;   Mn: 1.00% to 4.00%;   sol. Al: 0.001% to 2.000%;   Si+sol.Al: 1.00% or more;   Ti: 0.010% to 0.380%;   P: 0.100% or less;   S: 0.0300% or less;   N: 0.1000% or less;   O: 0.0100% or less;   Nb: 0% to 0.100%;   V: 0% to 0.500%;   Cu: 0% to 2.00%;   Cr: 0% to 2.00%;   Mo: 0% to 1.00%;   Ni: 0% to 2.00%;   B: 0% to 0.0100%;   Ca: 0% to 0.0200%;   Mg: 0% to 0.0200%;   REM: 0% to 0.1000%;   Bi: 0% to 0.020%;   one or more of Zr, Co, Zn and W: 0 to 1.00% in total,   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 comprises, by area %,
 retained austenite: 10% to 20%, 
 fresh martensite: 10% or less, and 
 bainite: 70% to 90%, 
   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 to 8.0, 
   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 2.0 to 4.0, and a tensile strength of the hot-rolled steel sheet is 980 MPa or more. 
   
     
     
         2 . The hot-rolled steel sheet according to  claim 1 , wherein the chemical composition comprises by mass %, one or more of
 Nb: 0.005 to 0.100%,   V: 0.005 to 0.500%,   Cu: 0.01 to 2.00%,   Cr: 0.01 to 2.00%,   Mo: 0.01 to 1.00%,   Ni: 0.02 to 2.00%,   B: 0.0001 to 0.0100%,   Ca: 0.0005 to 0.0200%,   Mg: 0.0005 to 0.0200%,   REM: 0.0005 to 0.1000%, and   Bi: 0.0005 to 0.020%.