| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength hot rolled steel sheet having a tensile strength TS of 1,180 MPa or higher and having excellent bendability, and an advantageous method for producing the same.SOLUTION: A steel slab comprising, by mass, C of 0.1 to 0.4%, Si of 0.2% or lower, Mn of 1.5% or lower, P of 0.03% or lower, S of 0.03% or lower, Al of 0.1% or lower and N of 0.005% or lower, and further comprising proper amounts of one or more kinds selected from Ti, Nb and Zr and also one or more kinds selected from Mo, V and W and obtained by being subjected to continuous casting is cooled from a solidification point to 1,300°C at 10 to 300°C/min, is thereafter charged to a heating furnace without being cooled to below 900°C, is reheated at 1,150 to 1,300°C for 40 min or lower, is subjected to hot rolling in which finish rolling is finished at 820°C or higher and is coiled around a coil at 700 to 500°C to obtain a hot rolled steel sheet having a steel structure of a ferrite single phase and having a tensile strength of 1,180 MPs or higher. |
