Q390C连铸坯CCT曲线测定及组织演变分析

CCT CURVE DETERMINATION AND MICROSTRUCTURE EVOLUTION ANALYSIS OF Q390C CONTINUOUS CASTING SLAB

根据Gleeble-3500 热模拟机上测定的不同冷却速率下连续冷却时Q390C的膨胀曲线,结合金相-硬度法得出了Q390C的连续冷却转变曲线;根据CCT曲线和金相分析结果,分析不同冷却速率条件下Q390C的组织转变情况,探究冷却速率对Q390C组织演变和硬度的影响。结果表明:Q390C相变温度A_(c1)和A_(c3)分别为738.3 ℃、834.9 ℃;冷却速率低于0.5 ℃/s时,所得组织为铁素体、珠光体和渗碳体;冷却速率在0.5~20 ℃/s之间,所得组织为贝氏体、马氏体以及残余奥氏体;冷却速率超过50 ℃/s时,所得组织为马氏体和残余奥氏体。研究结果为Q390C生产实践和工艺参数优化提供了理论依据。

According to the expansion curve of Q390C under different cooling rates measured on the Gleeble-3500 thermal simulator, the continuous cooling transformation curve of Q390C is obtained by combining the metallographichardness method;according to the CCT curve and metallographic analysis results, the microstructure transformation of Q390C under different cooling rates is analyzed, and the effect of cooling rate on the microstructure evolution and hardness of Q390C is explored. The results show that the phase transition temperatures A_(c1) and A_(c3) of Q390C are 738.3 ℃ and 834.9 ℃;when the cooling rate is lower than 0.5 ℃/s, the obtained microstructures are ferrite, pearlite and cementite;when the cooling rate is between 0.5~20 ℃/s, the obtained microstructures are bainite, martensite and retained austenite;when the cooling rate exceeds 50 ℃/s, the obtained microstructures are martensite and retained austenite;The research results provide a theoretical basis for Q390C production practice and process parameter optimization.