Efeito dos tratamentos térmicos de solubilização e envelhecimento na microestrutura e na resistência mecânica das ligas de alumínio A354 e 2024 fundidas

Abstract

Aluminum has several applications in various segments of the market. In engineering, as a material alternative, three emerging sectors contributed to leverage the applicability of aluminum alloys in several sectors, such as electricity and electronic equipment, automotive, aeronautics and aerospace. In the automotive sector, aluminum alloys in general are used in different components of the light and heavy automotive line, for example: in combustion engines, steering and damping components and turbo-compressor. The A354 alloy is used in turbocharger rotors, due to its low density and high mechanical resistance. There are some application limitations, as they present a limit of tensile strength, around 390 MPa, which makes its use impracticable, due to the recurring requests in a short period of time, mainly in urban perimeter vehicles. However, the present work aimed to evaluate the effect of heat treatments of solubilization and aging on the microstructure and on the mechanical tensile properties of the A354 and 2024 vacuum-cast alloys. The samples of the molten A354 alloy were treated by solubilization at 526°C for 10 h and aged at 160°C for 10 h. For the samples of the molten 2024 alloy, the solubilization treatments were carried out at 490 ° C, 500°C and 510°C and maintained for 1 h, and cooled in water, and the aging treatments were carried out at temperatures of 190°C, 200°C and 210°C for 1 h, for periods of 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, 24 h and 48 h. Subsequently, the specimens were cooled in the air. The procedures for analyzing the samples of alloys A354 and 2024, consisted of chemical composition analysis, optical microscopy, scanning electron microscopy, dispersive energy spectroscopy, X-ray diffraction, thermal analysis, hardness and tensile test. The results indicated that the A354 alloy solubilized at 526°C and aged at 160°C for 10 h, did not show an increase in the tensile strength limit. The alloy 2024 solubilized at 510°C / 1 h and aged at 210°C for 1 h, presented a higher limit of tensile strength when compared to alloy A 354, reaching a limit of tensile strength of 460 MPa. Alloy 2024 has the potential to replace alloy A354 currently applied for the production of turbocharger rotors.