Effects of tantalum on austenitic transformation kinetics of RAFM steel
Jian-guo Chen,Yong-chang Liu,Chen-xi Liu,Bi-yu Yan,Hui-jun Li
State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University, Tianjin 300350, China
Effects of tantalum on austenitic transformation kinetics of RAFM steel
Jian-guo Chen,Yong-chang Liu,Chen-xi Liu,Bi-yu Yan,Hui-jun Li
State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University, Tianjin 300350, China
ժҪ The RAFM (reduced activation ferritic/martensitic) steels containing different tantalum contents (0 wt.%, 0.027 wt.%, 0.073 wt.%) were designed and cast. Differential scanning calorimetry and optical microscopy were employed to explore the influence of tantalum content on the austenitic transformation of RAFM steels. The austenitic transformation kinetics was described by a phase-transformation model. The model, involving site saturation nucleation, diffusion-controlled growth and impingement correction, was established based on the classical Johnson-Mehl-Avrami-Kolmogorov model. The phase-transformation kinetics parameters, including D0 (pre-exponential factor for diffusion) and Qd (activation energy for diffusion), were calculated by fitting the experimental data and the kinetic model. The results indicated that the average grain size is decreased with the increase of tantalum. The values of Ac1 and Ac3 (onset and finish temperature of austenitic transformation, respectively) are increased by increasing the tantalum content. The increase of tantalum caused the decrease of D0. However, Qd is increased with the increase of tantalum. In addition, as a carbides forming element, tantalum would reduce the carbon diffusion coefficient and slow down the austenitic transformation rate.
Abstract��The RAFM (reduced activation ferritic/martensitic) steels containing different tantalum contents (0 wt.%, 0.027 wt.%, 0.073 wt.%) were designed and cast. Differential scanning calorimetry and optical microscopy were employed to explore the influence of tantalum content on the austenitic transformation of RAFM steels. The austenitic transformation kinetics was described by a phase-transformation model. The model, involving site saturation nucleation, diffusion-controlled growth and impingement correction, was established based on the classical Johnson-Mehl-Avrami-Kolmogorov model. The phase-transformation kinetics parameters, including D0 (pre-exponential factor for diffusion) and Qd (activation energy for diffusion), were calculated by fitting the experimental data and the kinetic model. The results indicated that the average grain size is decreased with the increase of tantalum. The values of Ac1 and Ac3 (onset and finish temperature of austenitic transformation, respectively) are increased by increasing the tantalum content. The increase of tantalum caused the decrease of D0. However, Qd is increased with the increase of tantalum. In addition, as a carbides forming element, tantalum would reduce the carbon diffusion coefficient and slow down the austenitic transformation rate.
��������:China National Funds for Distinguished Young Scientists;National Natural Science Foundation of China;National Magnetic Confinement Fusion Energy Research Program
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E-mail: cxliutju@163.com
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Jian-guo Chen,Yong-chang Liu,Chen-xi Liu,Bi-yu Yan,Hui-jun Li. Effects of tantalum on austenitic transformation kinetics of RAFM steel[J]. �й������ڿ���, 2017, 24(7): 705-710.
Jian-guo Chen,Yong-chang Liu,Chen-xi Liu,Bi-yu Yan,Hui-jun Li. Effects of tantalum on austenitic transformation kinetics of RAFM steel. Chinese Journal of Iron and Steel, 2017, 24(7): 705-710.
2017, Vol. 24 
