Correlation of the Effects of Alloying Elements on the Hardenability of Steels to the Diffusion Coefficients of Elements in Fe
International Journal of Materials Science and Applications
Volume 6, Issue 4, July 2017, Pages: 200-206
Received: Jun. 21, 2017; Accepted: Jul. 5, 2017; Published: Jul. 17, 2017
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Author
Yoshiharu Mae, Maetech, Mimuro, Midori Ward, Saitama City, Japan
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Abstract
The effects of various alloying elements on the hardenability of steels are known experimentally, but the reasons for these effects are not well understood. In this work, the upper critical cooling rate was selected as the index of hardenability. Changes in the upper critical cooling rate of steel caused by the presence of alloying elements and the diffusion coefficients of those elements in the ã-phase of Fe, plotted on thermal conductivity–Young’s modulus diagrams, showed similar patterns. The correlation between these factors was studied. Good correlation was found: the upper critical cooling rate decreased linearly with increasing diffusion coefficient of the alloying element in the ã-phase, i.e., the hardenability increased. It is considered that a large diffusion coefficient of an alloy element in the ã-phase increases its entropy and, on cooling, thermodynamically stabilizes the ã-phase, thereby preventing its transformation to the á-phase and retaining the ã-phase at a lower temperature, which consequently favors martensitic transformation even at low cooling rates.
Keywords
Hardenability, Steel, Diffusion Coefficient, Young’s Modulus, Thermal Conductivity
To cite this article
Yoshiharu Mae, Correlation of the Effects of Alloying Elements on the Hardenability of Steels to the Diffusion Coefficients of Elements in Fe, International Journal of Materials Science and Applications. Vol. 6, No. 4, 2017, pp. 200-206. doi: 10.11648/j.ijmsa.20170604.16
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Copyright © 2017 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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