Estudo da influência dos envelhecimentos simples e duplex no comportamento à corrosão da liga ti-6al-4v

Abstract

Currently the Ti-6Al-4V alloy, which represents 90% of the titanium used in the aeronautical industry thanks to combinations of attractive properties such as workability, machining and resistance at high temperatures. Mainly used for applications that require resistance to high temperatures, as these conditions have high susceptibility of phase precipitation directly impacting on its mechanical properties and resistance to corrosion of the alloy due to considerable microstructural changes. The α + β alloys have a very sensitive property/microstructure relationship, their properties are greatly influenced by the morphology proportions and distribution of the α and β phases. The samples of this alloy were solubilized and subjected to simple and duplex aging, and these conditions were analyzed for electrochemical behavior by means of corrosion testing in a 2M HCl solution, resulting in a drop in corrosion resistance of the alloy with current densities of 2.8x10-4 A.cm2 (simple aging) and 3.08x10-4 A.cm2 (duplex aging). Optical microscopy techniques were also used where it was possible to observe the formation of the αp (primary alpha), βt (transformed beta), β metastable phases in the solubilization of the samples and, in the aged samples, the presence of allotiomorphs α phase, Widmanstätten structure, precipitation and growth of α phase in the center of the grains. The samples submitted to aging showed less resistance to corrosion, suffering corrosion throughout the test and without formation of passive layer.