| Abstract Scope |
Laser heat treatments offer a reliable way to enhance steel surfaces, thanks to their effectiveness and suitability for automation. Several studies have summarized the technological advantages and main features of laser heat treatments [1–5], yet none of them have addressed the importance of the initial microstructure as a design parameter.
A model for the formation of austenite during laser heat treatment is hereby proposed, which considers a fully pearlitic structure as initial condition. The microstructural parameters of the model are the pearlitic colony size (radius) and interlamellar spacing. The depth variation of hardness is implemented as a correlation of the fraction of austenite transformed to martensite and its carbon content. The model was validated by performing controlled laser experiments in a fully pearlitic AISI 1095. The resulting microstructure was subject to in-depth characterization using electron back-scattering diffraction (EBSD) and high-resolution scanning electron microscopy.
The results indicate that there is a correlation between the extent of the hardened and transition layers with both colony radius and interlamellar spacing, which is due to the impact of these variables on the fraction of austenite. Comparison of the model and experimental observations of the microstructure suggest that the formation of austenite under fast heating rates occur with negligible overheating.
[1] M. Bamberger, Laser surface hardening of structural ferrous alloys, International Materials Reviews 43 (1998). https://doi.org/https://doi.org/10.1179/imr.1998.43.5.189.
[2] J. Dutta Majumdar, I. Manna, Laser material processing, International Materials Reviews 56 (2011) 341–388. https://doi.org/10.1179/1743280411Y.0000000003.
[3] P. Dinesh Babu, K.R. Balasubramanian, G. Buvanashekaran, Laser surface hardening: a review, Int. J. Surface Science and Engineering 5 (2011) 131–151.
[4] J. Mazumder, Laser Heat Treatment: The State of the Art, JOM 35 (1983) 18–26. https://doi.org/10.1007/BF03338273.
[5] O. Kapustynskyi, N. Višniakov, The Influence of Heat Treatment and Laser Alternative Surface Treatment Methods of Non-Alloy Steels: Review, Photonics 12 (2025). https://doi.org/10.3390/photonics12030207. |