N含量对Nb微合金化HRB400E钢筋组织与性能的影响

摘要：为了更好地发挥N元素在Nb微合金化钢筋中的作用，降低生产成本以及为钢筋成分设计提供理论依据。利用金相显微镜、扫描电镜、透射电镜、力学试验机对不同N含量的Nb微合金化高强抗震钢筋进行显微组织表征及力学性能测试，探究N含量对Nb微合金化钢筋的组织与力学性能的影响。研究表明，轧制过程中的奥氏体组织，随着N含量的增加，平均奥氏体晶粒有所减小；最终组织为铁素体和珠光体，随着N含量的增加，铁素体平均晶粒尺寸而减小，片层状珠光体的连续性增加，片层间距减小；析出相Nb(C，N)随着N含量的增大，沉淀析出的第二项颗粒体积分数增大，颗粒尺寸随之减小；在力学性能方面，屈服强度逐渐增加，抗拉强度先增加后减少。

Effect of N content on microstructure and properties of Nb microalloyed HRB400E rebar

Abstract： The purpose of this study is to better play the role of N in Nb microalloyed rebars, in order to reduce production costs and provide a theoretical basis for the design of rebars. Using metallographic microscope, scanning electron microscope, transmission electron microscope, and mechanical testing machine to carry out microstructure characterization and mechanical performance test of different N content of Nb microalloyed high strength seismic rebars, and explore the effect of N content on the structure and mechanics of Nb microalloyed high strength anti seismic rebars. The results show that the austenite structure during the rolling process decreases with the increase of N content; the final structure is ferrite and pearlite. As the N content increases, the average ferrite grain size and the interlamellar spacing decreases, but the continuity of lamellar pearlite increases. In Nb microalloyed high strength anti seismic rebars, the precipitated phase is Nb(C,N). With the increase of N content, the number of precipitated phase and the second particle volume fraction of precipitation increases, but the particle size decreases accordingly. In terms of mechanical properties, the yield strength gradually increases, and the tensile strength shows a phenomenon of increasing first and then decreasing.