And a method of manufacturing the same high-strength hot-rolled steel sheet strength and ductility is isotropic and, excellent Aresho during molding pickling, chemical conversion treatment resistance, fatigue properties, hole expansion, and

摘要

In mass%, this high-strength hot-rolled steel sheet, C: 0.05~0.12%, Si: 0.8~1.2%, Mn: 1.6~2.2%, Al: 0. 30~0.6%, P: 0.05% or less, S: 0.005% or less, and N: and containing less than 0.01%, the balance includes unavoidable impurities and Fe, the metal structure is the metal structure, or consist of retained austenite phase of 0-1% area and less than martensite phase of 10% area and more than ferrite phase of 60 area% or more, 10% area and more than ferrite phase of 60% or more area consists of residual austenite phase of 0-1% area and less than bainite phase of 5% area and less than martensite phase, in the range of up to 500nm in thickness, it is detected by glow discharge optical emission spectroscopy from the surface of the steel sheet after pickling the maximum concentration of Al is 0.75 mass% or less.