Abstract
The kinetics of phase transformations is usually described by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. The article shows that this equation cannot give a sufficiently general description of austenitization kinetics of ferritic nodular cast iron. Therefore, another kinetics equation is proposed which catches the main circumstances and substance of austenitization more accurately than the JMAK equation does. It shows that the crucial phenomena in the transformation are not only the processes of the creation and growth of new austenite grains but also the change in specific volume and the chemical liquation of alloying additives, which retard the subsequent conversion. The proposed equation together with the Arrhenius equation allows describing simultaneously the temporal and temperature dependence of austenitization conversion including the partial transformation at insufficiently high overheating of transformed iron. It is verified by successful regression of experimental data, whose results allow drawing predictive curves for temperatures from the experimental temperature region or from its near vicinity, for which the conversion was not determined.
Similar content being viewed by others
References
Keough JR (1995) Foundry Manage Technol 123(11):27
Nath SK, Ray S, Mathur VNS, Kapoor ML (1994) ISIJ Int 34:191
Zhang W, Elmer JW, Debroy T (2002) Mater Sci Eng A 333:320
Elmer JW, Palmer TA, Zhang W, Wood B, Debroy T (2003) Acta Mater 51:3333
Elmer JW, Palmer TA, Babu SS, Zhang W, Debroy T (2004) Weld J 83:224S
Kumar A, Mishra S, Elmer JW, Debroy T (2005) Metal Mater Trans A 36:15
Johnson WA, Mehl RF (1939) Trans AIME 135:416
Avrami M (1939) J Chem Phys 7:1103
Kolmogorov AN (1937) Izv Akad Nauk SSSR, Ser Matem 3:355
Todinov MT (2000) Acta Mater 48:4217
Levine LE, Narayan KL, Kelton KF (1997) J Mater Res 12:124
Starink MJ, Zahra AM (1998) Philos Mag A 77:187
Schmidt U, Schmidt B (2000) Mater Sci Forum 331–333:889
Starink MJ (2001) J Mater Sci 36:4433
Starink MJ (2004) Int Mater Rev 49:191
Herfurth K, Giesserei-Praxis (2003) 99
Kohout J (1999) J Mater Sci 34:843
Kohout J (2004) J Phys IV 120:191
Kohout J (2007) Mater Sci Eng A 462:159
Dorazil E (1991) High strength austempered ductile cast iron. Horwood, London
Acknowledgements
Financial support of the Ministry of Defence of the Czech Republic within research project MO0 FVT0000404 is gratefully acknowledged. Moreover, the author is grateful to Prof. Herfurth (see [16]), whose original experimental results were used in author’s calculations.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Kohout, J. An alternative to the JMAK equation for a better description of phase transformation kinetics. J Mater Sci 43, 1334–1339 (2008). https://doi.org/10.1007/s10853-007-2255-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10853-007-2255-9