Caractérisation des propriétés mécaniques par nanoindentation d'un traitement de diffusion et d'un revêtement pour l'amélioration de la résistance à l'usure des aciers à bas carbone.

The superficial zone is very often the part of a component which undergoes the strongest constraints, it is also this zone which is exposed to frictions and the chemical attacks. The surface treatments are largely used to solve the problems of wear, chemical attack, corrosion or fatigue. This work concerns the development of a surface conversion treatment by diffusion precipitation. This process of superficial hardening allows to increase and to improve the superficial properties of materials and more particularly those of the tools. It is proposed in this work, to search the conditions for obtaining a chromium carbide known by these properties of wear, corrosion and oxidation resistance, starting from a treatment carried out in three stages: the first stage is a pack carburizing (pack cementation) by carbon on two low carbon steels: the XC18 and the 16MC5. The second stage, concerns the deposition on the surface of treated steels a metallic chromium film of a few μm. In the third stage the parts previously obtained are heated at high temperature to convert the surface chrome species into carbide by diffusion of carbon from the cemented zone towards surface chrome species to obtain by precipitation of chromium carbide. The characterization of the mechanical properties (hardness and Young modulus) by nanoindentation of the samples obtained is carried out in this work. [ABSTRACT FROM AUTHOR]