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Effect of electric current pulses on the microstructure and niobium carbide precipitates in a ferritic-pearlitic steel at an elevated temperature

Published online by Cambridge University Press:  15 September 2015

Alireza Rahnama Open the ORCID record for Alireza Rahnama [Opens in a new window]  and
R.S. Qin
Alireza Rahnama*
Affiliation:
Warwick Manufacturing Group (WMG), International Digital Laboratory (IDL), University of Warwick, Coventry CV4 7Al, United Kingdom
R.S. Qin
Affiliation:
Department of Engineering and Innovation, The Open University, Walton Hall, Milton Keynes MK7 6AA, Buckinghamshire, United Kingdom
*
a)Address all correspondence to this author. e-mail: [email protected]
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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.

Keywords

electromigrationphase transformationsteel
Type
Articles
Information
Journal of Materials Research , Volume 30 , Issue 20 , 28 October 2015 , pp. 3049 - 3055
Copyright
Copyright © Materials Research Society 2015 

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