含Nb热轧多相钢板厚度方向显微组织的研究

通过热轧实验研究了控轧控冷工艺和化学成分对两种含Nb微合金化钢厚度方向显微组织的影响。结果表明,从试样芯部到1/4厚度位置,再到表面层,铁素体晶粒和贝氏体束尺寸越来越小,相应位置处的铁素体量逐步增多,而M-A量则经历了先增加后减少的过程,并在1/4厚度位置处达到了峰值。在控轧控冷工艺参数相近的情况下,在厚度方向同一位置处,Nb-Ti钢的铁素体晶粒、贝氏体束以及M-A组元尺寸更小,并且厚度方向不同位置处的组织差异较Nb钢小,对减小厚度效应更为有利。

Study on the Microstructure through Thickness Direction of Hot Rolled Multiphase Steel Plates Containing Nb

Effects of thermomechanical controlled processing and chemical composition on the microstructure through thickness direction of Nb steel and Nb-Ti steel were investigated by hot rolling experiment.The results showed that ferrite grain and bainite packet were smaller and smaller,and ferrite amount was increased gradually from central region through a quarter of the thickness to surface layer of the specimen.Whereas M-A amount was increased firstly,then decreased and reached peak value in a quarter of the total thickness.Under the condition of similar TMCP parameters,ferrite grain,bainite packet and M-A constituent sizes were smaller of Nb-Ti steel at the same region through thickness direction,and microstructure difference in different regions of thickness direction was smaller than that of Nb steel,which was more favorable to reduce thickness effect.