变形温度对CSP热轧65Mn带钢相变行为的影响

Effect of deformation temperature on phase transformation behavior of hot rolled 65Mn steel produced by CSP process

利用ThermecMastor-Z型热模拟试验机模拟CSP工艺条件,辅以金相显微镜(OM)、扫描电镜(SEM)和维氏硬度计等,研究65Mn钢的连续冷却转变规律及变形温度对其等温相变的影响。绘制了65Mn钢的动态CCT曲线。结果表明,当轧后冷速小于2℃/s时,试验钢可获得铁素体和珠光体组织。随着冷速的增大,试验钢中将出现贝氏体和马氏体组织,硬度增大。当冷速大于40℃/s时,试验钢中的组织全为马氏体,硬度达到678.05HV。此外,在研究不同变形温度对65Mn钢等温相变的影响时发现,第2道次变形温度为920℃时,珠光体组织多呈片层状,硬度为271.86HV;随着变形温度的降低,试验钢中铁素体含量增加,珠光体球化趋势明显,粒状珠光体含量增多。当变形温度下降至860℃时,试验钢的硬度降低至252.21HV,有利于其后续深加工。

The thermecmastor-Z thermal simulation tester was used to simulate the CSP process conditions, coupled with metallographic microscope(OM), scanning electron microscope(SEM) and Vickers hardness tester, by which the continuous cooling transformation of 65 Mn steel and deformation and the effects of take-up temperature on its isothermal phase transition were studied. The dynamic CCT curve of 65 Mn steel was plotted. The results show that ferrite and pearlite can be obtained in the experimental steel when the cooling rate is less than 2 ℃/s. With the increase of cooling rate, bainite and martensite will appear in the experimental steel, and the hardness will increase. When the cooling rate is more than 40 ℃/s, the microstructure in the steel is all martensite, and the hardness reaches 678.05 HV. In addition, when studying the influence of different deformation temperatures on the isothermal phase transition of 65 Mn steel, it is found that when the second deformation temperature was 920 ℃, the pearlite is lamellar and the hardness is 271.86 HV. With the decrease of deformation temperature, the ferrite content in the experimental steel increases, the pearlite spheroidization trend is obvious, and the granular pearlite content increases. When the deformation temperature drops to 860 ℃, the hardness of the test steel decreases to 252.21 HV, which is conducive to its further processing.