Caracterização de conjugados produzidos pelo processo de revestimento por atrito

Abstract

Tribology is the segment of engineering that studies the phenomena that occur on the surfaces of materials when placed in contact with each other. One of the pillars of tribology is the study of wear and its mechanisms. It is known that one of the ways to delay or even avoid the wear of materials would be the deposition of a coating with more resistant materials for a given application. Among the coating techniques, one can highlight friction stir surfacing (FSS), which has attracted the interest of the academic and industrial communities as it is applicable to a wide variety of similar and dissimilar materials. This work aims to evaluate the influence of changes in the input parameters, namely, mean square roughness (Rq) of the substrate (0.43, 1.75 and 2.54 μm), rotation of the consumable rod (1500, 2250 and 3000 rpm) and deposition speed (190, 285 and 380 mm / min) on the efficiency and thermal control of the process, morphology and dimensions of the coated layer in addition to the metallurgical (microstructure and residual stress) and mechanical properties (microhardness and resistance to bending) of the conjugates. ASTM A36 steel was used as substrate and ABNT 4340 steel as consumable rod and the deposition of the coatings was carried out ina machining center. The deposition input parameters were selected according to a full factorial design with three levels. The best efficiencies were noted for the conjugates obtained with the lowest input parameters. However, for all deposition conditions, conjugates with uniform morphological aspects were obtained, with no apparent flaws. It was found that the substrate roughness influences the coating adhesion mechanism, however it has no significant influence on the temperature evolution during the process, on the coating geometry, on the microstructure, on the residual stress or on the mechanical properties (microhardness and resistance to bending). Rotation of the consumable rod and speed of deposition, significantly influence the morphological and dimensional aspect of the coating, the amount of energy that enters the process and, consequently, the cooling rate of the conjugates, causing variations in the mechanical properties and in the metallurgical behavior (microstructures generated and induced residual stresses).