14MnNbq钢中Nb的作用

Role of Nb in 14MnNbq Steel

14MnNbq钢是为满足我国制造大跨度桥梁而开发的新型微合金化用钢。文中通过对14MnNbq钢板进行模拟控轧控冷试验 ,利用光学显微镜、透射电子显微镜、电化学萃取相分析等检测分析技术和手段 ,分析了Nb及其碳氮化物在控制轧制和控制冷却各阶段的作用及其对钢材微观组织和性能的影响 ;分析指出 ,为了充分发挥Nb的作用 ,在精轧阶段未再结晶区应尽可能增加变形量 ,轧后冷速以及终冷温度可按现场条件进行适当控制 ,以保证Nb(CN)的充分析出 。

In order to meet the needs of China-made gigantic bridges with long spans, 14MnNbq steel was developed . It is a new type of microalloyed steel. In this paper, simulated controlled rolling and cooling is taken. The role of microalloyed element Nb and Nb(CN) in the process of deformation and their effects on microstructures and mechanical properties of 14MnNbq steel are analysed by means of optical microscope, TEM, electrical chemical phase extraction analysis and micrography analysis.It is pointed out that in period of non-recrystallization of finish rolling should increase the deformation increment as great as possible to give full play to Nb, The cooling speed after rolling and the temperature of finish cooling should be controlled properly according to working condition to ensure Nb(CN) to separate out adequately. It is proved that Nb possesses good fine-grain strenghening and medium precipitate-hardening effects.