Efeito do tratamento térmico T4 e T6 sobre microestrutura e dureza da liga de alumínio da série 6061

Abstract

In general, aluminum and its alloys have low density, good thermal and electrical conductivity and good resistance to corrosion. Its mechanical properties can be improved by inserting alloy elements, making aluminum versatile and excellent for engineering applications. The 6061 series alloys have magnesium and silicon as the main alloying elements. When subjected to thermal treatments of solubilization and aging, they form the magnesium silicate (Mg2Si), responsible for the hardening of the material. This work aims to make a study on the influence of the thermal treatments T4 and T6 on microstructural properties and the hardness of the 6061 series aluminum alloys in order to improve their mechanical properties, optimizing the time and increasing the hardness after the heat treatment. The parameters were considered in accordance with the provisions of the ASM Handbook. In the case of the T4 heat treatment: it was solubilized for 1h at 550 ° C, followed by rapid cooling and natural aging. For a T6 heat treatment: different parameters were used: the first with a solubilization time of 1 h at 530 ℃ and 8 h of aging at 170 ℃ for the first study. The second parameter for the T6 treatment starts with 1 hour of solubilization at 550 ℃ and 3 h of aging at 200 ℃. With this last parameter, it is possible to increase the hardness of the material and reduce the heat treatment time. Achieving the same results for the two parameters in T6. The samples were characterized by scanning electron microscopy (SEM), scattered electron diffraction technique (EDS), particle size and hardness tests. For the two T6 treatments, it reached a hardness of 16.4 HW and in the T4 treatment it reached a hardness of 12 HW. These results were corroborated through statistical analysis of Anova in Minitab®, both for hardness and grain size. According to the statistical analysis, an equal average grain size is established for the two cases of T6. As for the T4 treatment, the average grain size is equal to the material as received. A comparison of energy consumption was also made with their respective parameters established in the T6-Experimental and T6-ASTM processes, with the aid of the Amazonas energy consumption simulator, a total consumption of 5.535 kWh is established with the conventional parameters and a total consumption of 2895 kWh with experimental parameters. Thus, reducing the cost of energy consumption by 47%, presenting parallel responses, it also reduces the time in the process and increases the hardness, which are the main contributions of this research work.