Effect of Annealing Time on Microstructure and Mechanical Properties of Cold-Rolled Niobium and Titanium Bearing Micro-alloyed Steel Strips

作     者：CHEN Jun SHEN Xin-jun JI Feng-qin TANG Shuai LIU Zhen-yu WANG Guo-dong 

作者机构：State Key Laboratory of Rolling and AutomationNortheastern University 

出 版 物：《Journal of Iron and Steel Research International》 (Journal of Iron and Steel Research, International)

年 卷 期：2013年第20卷第9期

页      面：86-92页

核心收录：

学科分类：080503[工学-材料加工工程] 0806[工学-冶金工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0802[工学-机械工程] 0702[理学-物理学] 0801[工学-力学（可授工学、理学学位）] 080201[工学-机械制造及其自动化] 

基　　金：Sponsored by Fundamental Research Funds for Central Universities of China(N110607003) 

主　　题：Nb-Ti bearing micro-alloyed steel cold rolling annealing microstructure mechanical property 

摘      要：Effects of annealing time on microstructure of cold-roiled niobium-titanium bearing micro-alloyed steel strips were investigated by optical microscopy, scanning electron microscopy, electron back-scatter diffraction （EBSD） and transmission electron microscopy. The complete recrystallization annealing temperature of 670 ℃ and complete annealing time of 9 min were determined using Vickers-hardness testing and EBSD analysis. The ferrite mi-crostructure with spheric cementite particles and nano-scale precipitates of Nb（C,N） in matrix was obtained. The ki-netics of the ferrite grain growth is lowered due to ferrite grain boundaries pinned by the cementite particles, so the ferrite grain size of 5.5 μm remains unchanged among the annealing time ranging from 9 to 30 min. In addition, the strength of tested steel also keeps unchanged with the increase of annealing time. The higher yield strength of ap-proximately 420 MPa can be obtained by grain refinement and precipitation hardening and the higher elongation of approximately 40% and work-hardening exponent of approximately 0.2 can be gained due to grain refinement and presence of cementite particles, indicating that the balance of strength, ductility and forming property is realized.