Patent ID: 8535458

Claim:
A high-strength hot-rolled steel sheet comprising, on a mass percent basis, 0.03%-0.12% C, 0.5% or less Si, 0.8%-1.8% Mn, 0.030% or less P, 0.01% or less S, 0.005%-0.1% Al, 0.01% or less N, 0.035%-0.100% Ti, the balance being Fe and incidental impurities, and microstructures with a fraction of polygonal ferrite of 80% or more, the polygonal ferrite having an average grain size of 5 to 10 μm, wherein an amount of Ti present in a precipitate having a size of less than 20 nm is 70% or more of a value of Ti* calculated using expression (1): Ti*=[Ti]−48×[N]/14 (1) where [Ti] and [N] represent Ti content (percent by mass) and N content (percent by mass), respectively, of the steel sheet.