| 摘要 |
PROBLEM TO BE SOLVED: To provide a high tensile strength hot rolled steel plate having tensile strength of 590 MPa or more, especially the high tensile strength hot rolled steel plate good in stretch-flange formability and extensibility and excellent in workability, and a production method thereof.SOLUTION: A high tensile strength hot rolled plate has a component composition containing, by mass%, C:0.08% to 0.16%, Si:0.70% to 1.50%, Mn:0.50% to 1.00% or less, P:0.050% or less, S:0.005% or less, Al:0.070% or less, Cr:0.10 to 0.50% and the balance Fe with inevitable impurities, and a metal structure containing ferrite as a main phase and retained austenite as a second phase having a volume fraction of 15% or less. |
