| 摘要 |
The purpose of the present invention is to provide a high-strength hot rolled steel sheet with good formability, which has good magnetic characteristics and excellent punchability, while having a tensile strength of 780 MPa or more. A high-strength hot rolled steel sheet having a tensile strength of 780 MPa or more, which is characterized by having a component composition that contains, in mass%, 0.070-0.140% of C, 0.10-1.00% of Si, 1.00-1.80% of Mn, 0.050% or less of P, 0.0050% or less of S, 0.0080% or less of N, 0.010-0.100% of Al and 0.050-0.150% of Ti, with the balance made up of Fe and unavoidable impurities. This high-strength hot rolled steel sheet having a tensile strength of 780 MPa or more is also characterized in that: 95% by volume or more of a bainite structure is contained; 80% or more of carbides among all the carbide precipitates are dispersed at the grain boundaries of bainitic ferrite that constitutes the bainite structure; and 80% or more of all the carbide precipitates have an average particle diameter of 20-300 nm. |
