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The effect of porosity on the austenite to bainite transformation in powder metallurgy steels

Published online by Cambridge University Press:  31 January 2011

Virendra S. Warke ,
Richard D. Sisson Jr.  and
Makhlouf M. Makhlouf
Virendra S. Warke*
Affiliation:
Materials Science and Engineering Program, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
Makhlouf M. Makhlouf
Affiliation:
Materials Science and Engineering Program, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
*
a) Address all correspondence to this author. email: virendra.warke@bodycote.com
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Abstract

The effect of porosity on the kinetics of the austenite to bainite isothermal transformation in powder metallurgy steels was characterized using a high-speed quenching dilatometer. The measurements revealed that the presence of porosity shortens the incubation time as well as the overall isothermal transformation time. An Avrami-type equation was fitted to the measured data, and the effect of porosity on the nucleation rate of bainite was quantified. In addition, the activation energy for diffusion of carbon atoms during nucleation of bainite was calculated and was found to decrease with increasing porosity.

Keywords

KineticsNucleation & growthPhase transformation
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 10 , October 2009 , pp. 3213 - 3219
Copyright
Copyright © Materials Research Society 2009

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