钛微合金化热轧双相钢的工艺研究

通过模拟实验研究了钛微合金化热轧双相钢的连续冷却转变曲线及终轧温度对组织的影响规律,获得了可行的工艺窗口,并进行了验证性热轧实验.在冷却速率小于5℃·s^-1及温度在625~725℃时,实验钢可以形成先共析铁素体.随着终轧温度升高,组织中铁素体及马氏体含量先升高后降低,但幅度不大.同时,当终轧温度较高时,铁素体显微硬度增加,析出强化作用增加.当终轧温度及缓冷温度分别为840℃及700℃时,获得了抗拉强度为672 MPa及屈强比为0.61的性能良好的热轧双相钢.经计算,铁素体组织中析出强化量为78.5 MPa.

Investigation on processing for a titanium-microalloyed hot rolled dual phase steel

Continuous cooling transformation curves were established and the influence of finish rolling temperature on the microstructure was investigated for a titanium-microalloyed dual phase steel through simulation experiment. A feasible process based on simulation experiment was obtained and confirmatory experiment was performed. It was found that pro-eutectoid ferrite could form in the steel when the cooling rate was less than 5℃·s-1 at a temperature of 625 to 725℃. The amount of ferrite and martensite increased firstly and then decreased slightly with the increasing of finishing rolling temperature. A higher hardness of ferrite was obtained at a higher finish rolling temperature because of precipitation strengthening. Better performance with a tensile strength of 672 MPa and a yield ratio of 0.61 was obtained for the steel when the finish rolling and slow cooling temperatures were 840℃ and 700℃,respectively. The amount of this precipitation strengthening was about 78.5 MPa based on calculations.