| 摘要 |
The present invention provides: a high-strength hot-rolled steel sheet having excellent stretch-flangeability and fatigue properties; and a production method therefor. The high-strength hot-rolled steel sheet has a tensile strength of at least 590 MPa and excellent stretch-flangeability and fatigue properties, as a result of having: a composition containing, in percent by mass, more than 0.020% but no more than 0.060% C, no more than 0.40% Si, more than 0.50% but no more than 1.20% Mn, no more than 0.030% P, no more than 0.030% S, no more than 0.10% Al, no more than 0.0100% N, and 0.050%-0.110% Ti, with the remainder being Fe and unavoidable impurities; a structure whereby the ferrite phase area ratio thereof is at least 95%, the solid solution C amount in the steel is at least 0.010%, a carbide that includes Ti is finely precipitated inside the crystal particles of the ferrite phase, and the average particle diameter of the carbide is less than 8 nm; and an internal oxidation in the steel sheet surface layer of no more than 0.15 g/m2. |
