| 摘要 |
<p>There is provided a high-strength hot-rolled steel sheet having excellent strength and formability (stretch flange formability) and a method for manufacturing the high-strength hot-rolled steel sheet. The high-strength hot-rolled steel sheet has a composition including C: 0.005% or more and 0.050% or less, Si: 0.2% or less, Mn: 0.8% or less, P: 0.025% or less, S: 0.01% or less, N: 0.01% or less, Al: 0.06% or less, and Ti: 0.05% or more and 0.10% or less, on a mass percent basis, such that S, N, and Ti satisfy Ti ‰¥ 0.04 + (N/14 x 48 + S/32 x 48), the remainder being Fe and incidental impurities; a matrix in which a ferrite phase constitutes 95% by area or more of the entire structure; and a structure in which Ti-containing fine carbide having an average grain size of less than 10 nm is dispersedly precipitated, and the volume ratio of the fine carbide to the entire structure is 0.0007 or more. The high-strength, hot-rolled steel sheet has a tensile strength of 590 MPa or more and excellent formability.</p> |
