| 摘要 |
A method for producing a cold rolled steel sheet having a tensile strength = 1470 MPa and a total elongation TE = 19%, the method comprising the steps of annealing at an annealing temperature AT = Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34 % = C = 0.40 %, 1.50 % = Mn = 2.30 %, 1.50 = Si = 2.40%, 0 % < Cr = 0.7%, 0 % = Mo = 0.3 %, 0.01 % = Al = 0.07 %, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT < Ms transformation point and between 150 °C and 250 °C, and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350°C and 420°C and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 250 seconds. |
