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Effects of tantalum on austenitic transformation kinetics of RAFM steel

Journal Article


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.

Publication Date


  • 2017

Citation


  • Chen, J. G., Liu, Y. C., Liu, C. X., Yan, B. Y., & Li, H. J. (2017). Effects of tantalum on austenitic transformation kinetics of RAFM steel. Journal of Iron and Steel Research International, 24(7), 705-710. doi:10.1016/S1006-706X(17)30106-1

Scopus Eid


  • 2-s2.0-85021843264

Start Page


  • 705

End Page


  • 710

Volume


  • 24

Issue


  • 7

Place Of Publication


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.

Publication Date


  • 2017

Citation


  • Chen, J. G., Liu, Y. C., Liu, C. X., Yan, B. Y., & Li, H. J. (2017). Effects of tantalum on austenitic transformation kinetics of RAFM steel. Journal of Iron and Steel Research International, 24(7), 705-710. doi:10.1016/S1006-706X(17)30106-1

Scopus Eid


  • 2-s2.0-85021843264

Start Page


  • 705

End Page


  • 710

Volume


  • 24

Issue


  • 7

Place Of Publication