Patent ID: 8157933

Claim:
A high-strength hot rolled steel sheet free from peeling and excellent in surface properties and burring properties, comprising, in terms of mass %, C: 0.03 to 0.1%, Si: 0.01 to 0.1%, Mn: 0.8 to 2.6%, P: not more than 0.1%, S: not more than 0.03%, Al: 0.001 to 1%, N: not more than 0.01%, Nb: 0.01 to 0.08%, and Ti: 0.04 to 0.2%, with a remainder being iron and unavoidable impurities, wherein if said Nb content is represented by [Nb], said C content is represented by [C], and said Ti content is represented by [Ti], then said steel sheet satisfies formulae below: [Nb]×[C]≦4.34×10 −3 , 0.0005≦[C]−(12/48[Ti]+12/93[Nb])≦0.005 a grain boundary density of solid solution C is not less than 1 atom/nm 2 and not more than 4.5 atoms/nm 2 , a grain size of cementite precipitated at grain boundaries within said steel sheet is not more than 1 μm, and a tensile strength is at least 780 MPa.