材料期刊网

通过Gleeble模拟一种高铌微合金管线钢控轧控冷过程,研究了其组织及相变特征和变形对相变过程的影响。由膨胀量变化分析及组织观察,建立了该钢的连续冷却相变CCT曲线。结果表明,铌元素及变形促进了针状铁素体的形成,采用两阶段控轧,当冷速由0.5℃/s增加到50℃/s时,组织由多边形铁素体、准多边形铁素体向针状铁素体转变,但冷速低于5℃/s时,组织转变对冷速变化较敏感,当冷速继续增加时,组织结构变化不明显,而基体中的M/A组元变得更细小、弥散。

Process of controlled hot rolling followed by controlled cooling of a Nb microalloyed pipeline steel was simulated on a Gleeble-1500D simulator and dilatometry measurements,microstructure and phase transformation characteristics of the steel and the effect of deformation on transformation were studied.According to the results of both dilatometry measurements and microstructure observations,the continuous cooling transformation curves（CCT） of the tested steel are constructed.The results show that Nb content and deformation enhance the formation of acicular ferrite,the microstructure of the steel ranges from PF,QF to AF with increasing of cooling rates from 0.5 to 50 ℃/s after two stage controlled rolling and the microstructure revolution is sensitive to cooling rates when it is lower than 5 ℃/s,however,when the cooling rate increases further,the microstructure does not change very much but M/A constituents in matrix is refined and dispersed.