Abstract: The effect of austenizing time (30 - 100 s) at 850 °C on structure and mechanical properties of 1 mm sheet of DF78O cold rolled dual phase steel (% ： 0.15C, 1.80Mn, 0.08Ti, 0.04Al) has been studied by using continuous annealing simulation machine. Results show that with conditions of austenizing at 850 X., cooling to 460 °C with 24 Y/s, retention for 12 s then cooling to ambient temperature with 7 Y/s, the martensite content in steel and tensile strength of steel could be controlled by change austenizing time: with decreasing austenizing time the martensite is continuously banded distribution and with prolonging austenizing time the continuity of banded martensite is weakening； as austenizing for 30, 45 and 100 s, the martensite content in the dual phase steel is respectively 13. 7% , 21. 6% and 15. 6% , and the tensile strength of steel is respectively 800, 840 and 805 MPa.

Key words: Dual Phase Steel, Austenizing Time, Martensite, Tensile Strength

摘要： 用连续退火模拟机研究了850℃奥氏体化时间(30～100 s)对1 mm厚DP780冷轧双相钢板(%:0.15C、1.80Mn、0.08Ti、0.04Al)组织和力学性能的影响。结果表明,当奥氏体化温度为850℃,以24℃/s冷却至460℃停留12 s,再以7℃/s冷却至室温的情况下,通过改变奥氏体化时间,可改变钢中马氏体含量和钢的抗拉强度。当奥氏体化时间较短时,马氏体呈带状连续分布,当奥氏体化时间较长时,马氏体带状连续性减弱;当奥氏体化时间在30、45、100 s时,该双相钢马氏体含量分别为13.7%、21.6%和15.6%,抗拉强度分别为800、840、805MPa。

关键词: 双相钢, 奥氏体化时间, 马氏体, 抗拉强度