DP980双相钢CCT曲线的测定与分析

Determination and Analysis of CCT Curves of Dual Phase Steel DP980

在Gleeble-1500D热模拟试验机上测定DP980双相钢的连续冷却相转变曲线（CCT曲线）,结合金相显微组织及维氏硬度,分析了不同冷却速度连续冷却时的组织转变,阐明了冷却速度与组织演变以及硬度变化的关系。结果表明：DP980钢在很大的冷速区间内都仅发生铁素体和贝氏体转变,只有当冷却速度达到50℃/s时,才开始发生马氏体转变。随冷速的提高,尤其在0.5～20℃/s时,硬相的贝氏体含量逐渐增加,硬度随冷速的提高增加的较为明显;冷却速率为20～50℃/s时,硬度提高趋于平缓。

The continuous cooling transformation （CCT） curves of dual phase steel were studied by Gleeble-1500 thermal- mechanical simulation. According to microscopic observation and hardness measurement, the transformation of microstructure at different cooling rates was analyzed, and the relationship between cooling rate, microstructure evolution and hardness was disclosed. The results show that DP980 steel only generates ferrite and bainite transformation within a large range of cooling rate. When the cooling rate reaches 50℃ / s, the martensite transformation just begins. With the increase of cooling speed, especially in the 0.5-20℃/s, the content of hard phase of bainite increases gradually, and the hardness increases more obviously with the increase of cooling rate. Under the cooling rate of 20-50℃/s, the increase of hardness tends to be gentle.