Kinetics and formation mechanisms of intragranular ferrite in V?N microalloyed 600 MPa high strength rebar steel
来源期刊：International Journal of Minerals Metallurgy and Materials2016年第4期
论文作者：Jing Zhang Fu-ming Wang Chang-rong Li
文章页码：417 - 424
摘 要：To systematically investigate the kinetics and formation mechanisms of intragranular ferrite（IGF）, isothermal heat treatment in the temperature range of 450℃to 600℃ with holding for 30 s to 300 s, analysis of the corresponding microstructures, and observation of the precipitated particles were conducted in V-N microalloyed 600 MPa high strength rebar steel. The potency of V（C,N） for IGF nucleation was also analyzed statistically. The results show that the dominant microstructure transforms from bainite（B） and acicular ferrite（AF） to grain boundary ferrite（GBF）, intragranular polygonal ferrite（IPF）, and pearlite（P） as the isothermal temperature increases from 450℃ to 600℃. When the holding time at 600℃ is extended from 30 s to 60 s, 120 s, and 300 s, the GBF content ranges from 6.0vol% to 6.5vol% and the IPF content increases from 0.5vol% to 2.8vol%, 13.1vol%, and 13.5vol%, respectively, because the ferrite transformation preferentially occurs at the grain boundaries and then occurs at the austenite grains. Notably, V（C,N） particles are the most effective nucleation site for the formation of IPF, accounting for 51% of the said formation.
Jing Zhang1,2，Fu-ming Wang1,2，Chang-rong Li3
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing2. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing3. School of Materials Science and Engineering, University of Science and Technology Beijing
摘 要：To systematically investigate the kinetics and formation mechanisms of intragranular ferrite（IGF）, isothermal heat treatment in the temperature range of 450℃to 600℃ with holding for 30 s to 300 s, analysis of the corresponding microstructures, and observation of the precipitated particles were conducted in V-N microalloyed 600 MPa high strength rebar steel. The potency of V（C,N） for IGF nucleation was also analyzed statistically. The results show that the dominant microstructure transforms from bainite（B） and acicular ferrite（AF） to grain boundary ferrite（GBF）, intragranular polygonal ferrite（IPF）, and pearlite（P） as the isothermal temperature increases from 450℃ to 600℃. When the holding time at 600℃ is extended from 30 s to 60 s, 120 s, and 300 s, the GBF content ranges from 6.0vol% to 6.5vol% and the IPF content increases from 0.5vol% to 2.8vol%, 13.1vol%, and 13.5vol%, respectively, because the ferrite transformation preferentially occurs at the grain boundaries and then occurs at the austenite grains. Notably, V（C,N） particles are the most effective nucleation site for the formation of IPF, accounting for 51% of the said formation.
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