| 摘要 |
Hot-rolled steel sheet having a strength of greater than 800 MPa, and an elongation at break of greater than 10%, comprises (wt.%): carbon (0.05-0.09); manganese (1-2); aluminum (0.015-0.05); silicon (0.1-0.3); molybdenum (0.1-0.4); sulfur (= 0.01); phosphorus (= 0.025); nitrogen (0.003-0.009); vanadium (0.12-0.22); titanium (= 0.009); niobium (= 0.02); and optionally chromium (= 0.45), where the rest of the composition is constituted of iron and unavoidable impurities resulting from elaboration. Independent claims are included for: (1) a weld assembly done by the steel sheet, where the sheet is welded by beam at high energy density; and (2) a preparation of the hot-rolled steel sheet comprising supplying the steel composition, casting of semi finished product from the steel, subjecting the semi finished product to a temperature of greater than 1150[deg] C, hot-rolling the semi finished product at end temperature of rolling (TFL), where the microstructure of the steel is entirely austenitic to obtain the sheet, then cooling the sheet at a cooling speed (VR) of 75-200[deg] C/second, and coiling the sheet at a winding temperature (Tbob) of 500-600[deg] C. |
