Continuous Cooling Transformation Behavior and Microstructure Control of Nb Microalloyed Reinforcing Bars  

作　　者：Zhang Yongqing Jose MRodriguez-Ibabe Beatriz Lopez Felipe Bastos Marcelo Rebellato 

机构地区：[1]China Iron&Steel Research Institute Group,No.76 Xueyuan Nanlu,Haidian,Beijing 100081,China [2]CITIC Metal Co.,Ltd,Room 1901 Capital Mansion,Beijing 100004,China [3]Ceit Research Institute P.M.Lardizabal 15,Donostia San Sebastian 20018,Spain [4]CBMM,Av.Brg.Faria Lima,4285,São Paulo-SP 04538-133,Brazil

出　　处：《Journal of Mechanics Engineering and Automation》2022年第3期77-91,共15页机械工程与自动化（英文版）

摘　　要：In this paper,CCT(continuous cooling transformation)diagrams are determined for Nb-containing reinforcing bars with different Nb,Mn additions,and initial austenite grain sizes by simulating industrial conditions via dilatometry tests.It was found that coarse austenite grain size,high Mn content and Nb remaining in solution all increase hardenability of Nb-containing rebars,namely lower Ar3 for acicular phase transformation products,which leads to continuous yielding during tensile deformation when the volume fraction of acicular ferrite or bainite microstructure reaches a certain volume fraction.By coupling with actual cooling rates for different size rebars,it can be explained why bainitic structure is prone to form in the center of rebars,especially for small size rebars.In order to achieve required ferrite-pearlite microstructure,cooling strategy is optimized for industrial production.

关 键 词：Nb microalloying HARDENABILITY CCT diagram continuous yielding 

分 类 号：TG1[金属学及工艺—金属学]