Hot-rolled steel sheet

Abstract

This hot-rolled steel sheet has a predetermined chemical composition and microstructure, in which, within regions obtained by dividing a sheet thickness cross section parallel to a rolling direction into three parts in a sheet thickness direction, when a pole density of the {001} plane of ferrite and bainite in a center region is P i , and a pole density of the {001} plane of ferrite and bainite in a surface layer region is P s , P i /P s is 1.2 to 2.0, and a tensile strength is 950 MPa or more.

1 . A hot-rolled steel sheet consisting of, as a chemical composition, in mass %,
 C: 0.02 to 0.30%,   Si: 0.10 to 2.00%,   Mn: 0.5 to 3.0%,   P: 0.100% or less,   S: 0.010% or less,   Al: 0.10 to 1.00%,   N: 0.0100% or less,   Ti: 0.06 to 0.20%,   Nb: 0 to 0.10%,   Ca: 0 to 0.0060%,   Mo: 0 to 1.00%,   Cr: 0 to 1.00%,   V: 0 to 0.40%,   Ni: 0 to 0.40%,   B: 0 to 0.0020%,   Cu: 0 to 1.00%,   Sn: 0 to 0.50%,   Zr: 0 to 0.050%, and   a remainder of Fe and impurities,   wherein a microstructure contains, in area %,   a total amount of ferrite and bainite: 30 to 47%,   tempered martensite: 50 to 70%,   fresh martensite: 3 to 10%,   within regions obtained by dividing a sheet thickness cross section parallel to a rolling direction into three parts in a sheet thickness direction, when a pole density of the {001} plane of ferrite and bainite in a center region is P i  and a pole density of the {001} plane of ferrite and the bainite in a surface layer region is P s , P i /P s  is 1.2 to 2.0, and   a tensile strength is 950 MPa or more.   
     
     
         2 . The hot-rolled steel sheet according to  claim 1 ,
 wherein the chemical composition contains, in mass %, one or more of   Nb: 0.01 to 0.10%,   Ca: 0.0005 to 0.0060%,   Mo: 0.02 to 1.00%,   Cr: 0.02 to 1.00%,   V: 0.01 to 0.40%,   Ni: 0.01 to 0.40%,   B: 0.0001 to 0.0020%,   Cu: 0.02 to 1.00%,   Sn: 0.01 to 0.50%, and   Zr: 0.001 to 0.050%.   
     
     
         3 . A hot-rolled steel sheet comprising, as a chemical composition, in mass %,
 C: 0.02 to 0.30%,   Si: 0.10 to 2.00%,   Mn: 0.5 to 3.0%,   P: 0.100% or less,   S: 0.010% or less,   Al: 0.10 to 1.00%,   N: 0.0100% or less,   Ti: 0.06 to 0.20%,   Nb: 0 to 0.10%,   Ca: 0 to 0.0060%,   Mo: 0 to 1.00%,   Cr: 0 to 1.00%,   V: 0 to 0.40%,   Ni: 0 to 0.40%,   B: 0 to 0.0020%,   Cu: 0 to 1.00%,   Sn: 0 to 0.50%,   Zr: 0 to 0.050%, and   a remainder of Fe and impurities,   wherein a microstructure contains, in area %,   a total amount of ferrite and bainite: 30 to 47%,   tempered martensite: 50 to 70%,   fresh martensite: 3 to 10%,   within regions obtained by dividing a sheet thickness cross section parallel to a rolling direction into three parts in a sheet thickness direction, when a pole density of the {001} plane of ferrite and bainite in a center region is P i  and a pole density of the {001} plane of ferrite and the bainite in a surface layer region is P s , P i /P s  is 1.2 to 2.0, and   a tensile strength is 950 MPa or more.