Abstract
Niobium is an important alloying element in steels. In the present work an effort has been made to investigate the effect of electropulsing on the niobium carbide (NbC) at an elevated temperature (800 °C). The results show that the electropulsing treatment can generate an evenly distributed NbC by decreasing the kinetics barriers for precipitation. It has been also found that a semitransformed pearlite structure forms in such a way that the grains are oriented toward a direction parallel to that of the electric current flow. Furthermore, the electropulsed sample benefits from refined grain size. This is thought to be due to the electropulse-enhanced nucleation rate. Tensile testing has been carried out to compare the properties of electropulsed sample with that of without electropulsing. The results show that the sample with treatment has greater yield strength and ultimate tensile stress while its elongation is only 1% less that of the unelectropulsed samples. The improved mechanical properties of the sample with pulsing are attributed to its finer grain sizes as well as the elimination of precipitation free zones caused by the electropulsing treatment.
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X. Ye, W. Lingsheng, Z.T.H. Tse, G. Tang, and G. Song: Effects of high-energy electro-pulsing treatment on microstructure, mechanical properties and corrosion behaviour of Ti-6Al4V alloy. Mater Sci. Eng., C 49, 851–860 (2015).
X.F. Zhang and R.S. Qin: Controlled motion of electrically neutral microparticles by pulsed direct current. Sci. Rep. 5, 10162 (2015).
L. Guan, G.Y. Tang, and P.K. Chu: Recent advances and challenges in electroplastic manufacturing processing of metals. J. Mater. Res. 25, 1215–1224 (2010).
J.P. Barnak, A.F. Sprecher, and H. Conrad: Colony (grain) size reduction in eutectic Pb–Sn castings by electropulsing. Scr. Metall. Mater. 32, 879–884 (1995).
H. Conrad: Effects of electric current on solid state phase transformations in metals. Mater Sci Eng., A 287, 227–237 (2000).
Y.Z. Zhou, R.S. Qin, S.H. Xiao, G. He, and B. Zhou: Reversing effect of electropulsing on damage of 1045 steel. J. Mater. Res. 15, 1056–1061 (2000).
Y. Onodora, A. Sakuma, and K.I. Hirano: Current dependence of the retardation of precipitation by direct-current stress in AI-3.3 at % Mg. J. Mater. Sci. 28, 3835–3838 (1993).
Y. Onodora, J.I. Maruyama, and K.I. Hirano: Retardation of the precipitation reaction by d.c. stress in an A1-12.5 wt. % Zn alloy. J. Mater. Sci. 12, 1109–1114 (1977).
N. Fujita and H.K.D.H. Bhadeshia: Modelling precipitation of niobium carbide in austenite: Multicomponent diffusion, capillarity, and coarsening. Mater. Sci. Technol. 17, 403–408 (2001).
P. Yan and H.K.D.H. Bhadeshia: Austeniteferrite transformation in enhanced niobium, low carbon steel. Mater. Sci. Technol. 31, 1066–1076 (2015).
A. Rahnama and R.S. Qin: Electropulse-induced microstructural evolution in a ferriticpearlitic 0.14% C steel. Scr. Mater. 96, 17–20 (2015).
A. Rahnama and R.S. Qin: The effect of electropulsing on the interlamellar spacing and mechanical properties o fa hot-rolled 14 wt.% carbon steel. Mater. Sci. Eng., A 627, 145–152 (2015).
Y. Dolinsky and T. Elperin: Thermodynamics of phase transitions in current carrying conductors. Phys. Rev. B 47, 14778–14785 (1993).
W.J. Lu, X.F. Zhang, and R.S. Qin: Stability of precipitates under electropulsing in 316L stainless steel. Mater. Sci. Technol, in press, doi: https://doi.org/10.1179/1743284714Y.0000000743.
X.L. Wang, X.L. Wang, J.D. Guo, Y.M. Wang, X.Y. Wu, and B.Q. Wang: Segregation of lead in Cu–Zn alloy under electric current pulses. Appl. Phys. Lett. 89, 061910 (2006).
Y. Liu, J. Fan, H. Zhang, W. Jin, H. Dong, and B. Xu: Recrystallization and microstructure evolution of the rolled Mg–3Al–1Zn alloy strips under electropulsing treatment. J. Alloys Compd. 622, 229–235 (2015).
Y.S. Zheng, G.Y. Tang, J. Kuang, and X.P. Zheng: Effect of electropulsing on solid solution treatment of 6061 aluminium alloy. J. Alloys Compd. 615, 849–853 (2014).
R.S. Qin and B.L. Zhou: Exploration on the fabrication of bulk nanocrystalline material by direct nanocrystallizing method II theoritical calculation of grain size of metals solidified under electropulsing. Chin. J. Mater. Res. 11, 69–72 (1997).
H. Conrad, N. Karam, and S. Mannan: Effect of electric current pulses on the recrystallization of copper. Scr. Mater. 17, 411–416 (1983).
S.H. Xiao, Y.Z. Zhou, J.D. Guo, S.D. Wu, G. Yao, S.X. Li, G.H. He, and B.L. Zhou: The effect of high current pulsing on persistent slip bands in fatigued copper single crystals. Mater. Sci. Eng., A 332, 351–355 (2002).
R.S. Qin, I. Samuel, and A. Bhowmik: Electropulse-induced cementite nanoparticle formation in deformed pearlitic steels. J. Mater. Sci. 46, 2838–2842 (2011).
Y.B. Jiang, G.Y. Tang, C.H. Shek, Y.H. Zhu, and Z.H. Xu: On the thermodynamics and kinetics of electropulsing induced dissolution of β and Mg17Al12 phase in an aged Mg–9Al–1Zn alloy. Acta Mater. 57, 4797–4808 (2009).
P.S. Ho and T. Kwo: Electromigration in metals. Rep. Prog. Phys. 52, 301–348 (1989).
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The authors wish to acknowledge the financial support from POSCO and the Royal Academy of Engineering at United Kingdom.
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Rahnama, A., Qin, R.S. Effect of electric current pulses on the microstructure and niobium carbide precipitates in a ferritic-pearlitic steel at an elevated temperature. Journal of Materials Research 30, 3049–3055 (2015). https://doi.org/10.1557/jmr.2015.268
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DOI: https://doi.org/10.1557/jmr.2015.268