Patent ID: 7682467

Claim:
A high-strength hot-rolled steel sheet, superior in workability, fatigue property, and surface quality, said high-strength hot-rolled steel sheet consisting essentially of: C in a range of 0.03 to 0.15 mass %; Mn in a range of 0.5 to 2 mass %; Al in a range of 0.01 to 0.1 mass %; P in a range of 0.038 to 0.072 mass %; and Cr in a range of 0.4 to 0.91 mass %, respectively, while controlling S to not more than 0.02 mass % (0% included), and Si to not more than 0.1 mass % (0% included), wherein a metallic structure has polygonal ferrite as the main phase, and contains martensite as a second phase; and wherein the high-strength hot-rolled steel sheet does not contain Nb and Ti.