Estudo das variações de dureza e microestrutura da liga de alumínio AA6351-T6 quando submetida a ciclos térmicos de recozimento, solubilização e precipitação

Abstract

In this work the microstructural variations and the hardness variations of the AA6351 aluminum alloy were analyzed after being subjected to different heat treatments. Several combinations of temperature and time were used for the recrystallization, solubilization and artificial precipitation of samples other than said metal alloy. First, the chemical composition of the aluminum alloy was determined by the spectroscopy test. The samples were subjected to tests of Rockwell hardness and Vickers microhardness as received and after being subjected to the heat treatments. After the preparation of metallographic techniques the microstructures of the samples could be observed under an optical microscope. As a result it was determined the Rockwell hardness and Vickers microhardness as a function of the temperature and the time of the heat treatments. Thus, it was verified that sample 5 presented the best combination of heat treatment parameters to potentiate the hardness and microhardness of the AA6351 aluminum alloy. The results lead to the conclusion that some samples may have undergone the phenomenon known as super-aging, as a consequence of the high temperature oscillations of the treatment furnace during the artificial precipitation stage. The microstructural phenomena associated with precipitation hardening could not be observed by optical microscopy, most probably because it is a mechanically worked alloy.