| 摘要 |
<p>Disclosed in the present invention are high-strength steel sheets with a tensile strength (TS) above 490MPa, a yield strength : above 355MPa and yet a corrosion resistance by adding copper (Cu), molybdenum (Mo) and tin (Sn) together with a manufacturing method thereof. The manufacturing method of high-strength steel sheets according to the present invention is characterized by comprising; a step of reheating slab sheet materials containing ; carbon (C) : 0.03~0.15%, silicon (Si) : less than 0.6%, manganese (Mn) : 0.5~1.8%, phosphor (P) : less than 0.02%, sulfur (S) : less than 0.01%, chromium (Cr) : less than 0.5%, nickel (Ni) : 0.1~1.0%, molybdenum (Mo) : 0.1~1.0%, aluminum (Al) : less than 0.1%, copper (Cu) : 0.1~0.5%, titanium (Ti) : 0.005~0.05%, niobium (Nb) : 0.005~0.05%, vanadium (V) : 0.01~0.1%, boron (B) : 0.0001~0.005%, nitrogen (N) : less than 0.007%, tin (Sn) : 0.0005~0.01% in addition to a balance of iron (Fe) and unavoidable impurities; and a step of first rolling of the reheated sheet materials; and a step of second rolling of the first-rolled sheet materials under a finish rolling temperature condition of 800~850°C; and a step of cooling down the second-rolled sheet materials to 450~600°C. [Reference numerals] (AA) START; (BB) END; (S110) Reheat a slab; (S120) Primary rolling; (S130) Secondary rolling; (S140) Cooling</p> |
