In Situ Observation of Microstructure Evolution in Low Carbon Bainite Steels Isothermally Held Below A1 Temperature
|Periodical||Materials Science Forum (Volumes 654 - 656)|
|Edited by||Jian-Feng Nie and Allan Morton|
|Citation||Rui Zhang et al., 2010, Materials Science Forum, 654-656, 126|
|Online since||June, 2010|
|Authors||Rui Zhang, Shan Wu Yang, Chao Sun, Xin Lai He|
|Keywords||In Situ Observation, Low Carbon Bainite Steel, Micro-Structure Evolution|
The dominant microstructures in low carbon bainite steels such as bainitic ferrite are non-equilibrium phases, which will tend to evolve into equilibrium phases when the steels are subjected to thermal disturbance. In-situ observation by optical and scanning electron microscopy was carried out in this investigation to track the evolution when the steels were isothermally held below A1 temperature. It is found that the primary polygonal ferrite grows slowly during isothermal holding, while bainitic ferrite changes rapidly into polygonal ferrite. Self-tempered bainitic ferrite would recover further and recrystallize. The lower the concentration product of carbon and niobium, the faster is the evolution.