Nb和V微合金化对薄带铸轧高强钢相变行为的影响  

Effect of Nb and V microalloying on phase transformation behavior of strip casting high-strength steels

作　　者：曹锐 许帅 高军恒 冯庆晓 刘志桥 李化龙 CAO Rui;XU Shuai;GAO Junheng;FENG Qingxiao;LIU Zhiqiao;LI Hualong(Innovation Research Institute Carbon Neutrality,University of Science and Technology Beijing,Beijing 100083,China;Jiangsu(Shagang)Iron and Steel Research Institute,Zhangjiagang 215625,Jiangsu,China)

机构地区：[1]北京科技大学碳中和创新研究院,北京100083 [2]江苏省(沙钢)钢铁研究院,江苏张家港215625

出　　处：《钢铁研究学报》2023年第11期1430-1437,共8页Journal of Iron and Steel Research

摘　　要：薄带铸轧作为钢铁行业近终形制造技术的典型代表,钢液在浇铸阶段的凝固速度可达到10~2~10~4℃/s,铸带无需经历冷却再加热直接进行一道次热轧,因此合金元素大部分固溶于基体中,在微合金化技术方面有着广阔的应用前景。但目前对于薄带铸轧微合金钢的研究多集中于其团簇和析出行为,缺乏微合金元素对薄带铸轧相变行为的系统研究。以Q550-Nb和Q550-V为研究对象,通过连续冷却相变与等温相变2种实验,绘制了其静态CCT曲线,统计了不同条件下铁素体转变的体积分数,讨论了在薄带铸轧工艺下Q550-Nb和Q550-V两种实验钢的相变规律。结果表明,Q550-Nb比Q550-V更容易发生低温相变,Nb对铁素体相变的抑制作用更强;之后通过等温相变实验进一步证明了Q550-Nb的铁素体相变更为缓慢,主要由于Nb在两相界面偏聚的程度更强导致,限制了相界面迁移。通过TEM分析2种实验钢在等温过程中的相间析出行为,发现Q550-Nb相间析出的片间距比Q550-V更大,证明了Nb对相界面的拖曳作用更强。明确了2种微合金元素在薄带铸轧工艺中对相变的影响机制,为微合金化技术在薄带铸轧流程中的应用提供理论和技术支撑。As a representative technology of near-net-shape continuous casting in iron and steel industry,steel strip can be produced from molten steel directly.The typical technological characteristics of strip casting are high solidification rate(102-104℃/s),direct rolling(no reheating process)and one pass hot rolling.Therefore,most of the alloy elements are retained in the matrix in solid solution state because of its rapid solidification rate and single pass rolling,which render microalloying technology has broad application prospects in strip casting.However,currently,the hot research topics are the formation mechanisms of clusters and nanoprecipitates and their strengthening mechanisms in steel strips fabricated by strip casting,while systematic research on the effect microalloying elements on the phase transformation behavior of strip steel is still scarce.Here,the strip casting microalloyed steels Q550-Nb and Q550-V were investigated.Through continuous cooling transformation and isothermal transformation experiments,their static CCT curves and the volume fractions of ferrite transformation under different conditions were obtained,and the influence of alloying elements,V and Nb on the phase transformation behaviors of Q550-Nb and Q550-V experimental steels strips was discussed.The results show that in comparison with Q550-V,phase transformation tends to occur at lower temperature in Q550-Nb,suggesting that Nb has a stronger postponing effect on ferrite transformation.The results of isothermal transformation experiments show that Q550-Nb has a slower ferrite phase rate due to the greater extent of Nb segregation at phase interface that restricts the migration of phase boundaries.The interphase precipitation behavior of the two experimental steels using TEM were further studied and the results show that the nanoprecipitates row spacing of Q550-Nb is larger than that of Q550-V,which can be attributed to the stronger dragging effect of Nb on the phase boundary migration.The effect of microalloying elements,Nb and V,on

关 键 词：薄带铸轧 微合金化 铁素体相变 局域平衡模型 

分 类 号：TG142.1[一般工业技术—材料科学与工程]