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Elaboration de revêtements sur acier inoxydable: simulation de la fusion par irradiation laser, caractérisation structurale, mécanique et tribologique.

Abstract : A pulsed Nd-YAG laser is used to irradiate and alloy X30Cr13 stainless steel by surface melting, with incorporation of boron or hexagonal boron nitride (h-BN), and to obtain thick coatings: multiphase borided alloys or metal-ceramic composites. The metallographic analyses allow to determine the thickness for each coating (melting zone) and reveal characteristic solidification microstructures: planar front and cellular dendrites. Optical characteristics of the laser beam are measured: divergence, focal length spot radius and power distribution in the focal plane. Heat effect simulations are based on the finite difference modelling of the temporal progression of temperature distribution in the steel irradiated by scanning of the pulsed beam. Melting zone thickness is computed and progression of melting front during irradiation is simulated and so, a better description of the conditions of material incorporation by successive meltings and solidifications becomes possible. The mechanical properties, elastic modulus and hardness, of the different coatings are determined from nanoindentation tests. Under optimal irradiation conditions, the hardness reaches 14 GPa for composite coating and 10 GPa for borided alloy, whereas that for untreated steel is 4 GPa. Friction and wear tests are systematically performed in a ball-on-disc configuration, at 25 °C under various loads (1 to 10 N), then at 300 and 500 °C under 2 N. At ambient temperature, the dry sliding on ruby ball of these two types of coatings is characterized by a reduced friction coefficient and a weak wear rate, compared with the untreated steel, revealing a very reinforced resistance towards adhesive and/or abrasive wear. On the other hand, their wear resistance is decreased from 300 °C, in the spite of the significant lowering of friction coefficient.
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https://pastel.archives-ouvertes.fr/pastel-00000681
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Thursday, September 9, 2010 - 11:34:53 AM
Last modification on : Friday, July 17, 2020 - 2:53:31 PM
Long-term archiving on: : Friday, September 10, 2010 - 3:19:30 PM

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  • HAL Id : pastel-00000681, version 1

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Ludovic Avril. Elaboration de revêtements sur acier inoxydable: simulation de la fusion par irradiation laser, caractérisation structurale, mécanique et tribologique.. Sciences de l'ingénieur [physics]. Arts et Métiers ParisTech, 2003. Français. ⟨NNT : 2003ENAM0016⟩. ⟨pastel-00000681⟩

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