Title

EFEITO DO ENVELHECIMENTO ARTIFICIAL NAS PROPRIEDADES MECÂNICAS DA LIGA DE ALUMÍNIO 2024 PARA APLICAÇÕES AERONÁUTICAS

EFFECT OF THE ARTIFICIAL AGING ON MECHANICAL PROPERTIES OF 2024 ALUMINUM ALLOY FOR AERONAUTICAL APPLICATIONS

Authorship

Couto, Antonio Augusto; Reis, Danieli Aparecida Pereira; Junior, Nilton Inácio Domingues; Hirschmann, Ana Cláudia Oliveira; Zepka, Susana; Neto, Carlos de Moura

Couto, Antonio Augusto

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Reis, Danieli Aparecida Pereira

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Junior, Nilton Inácio Domingues

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Hirschmann, Ana Cláudia Oliveira

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Zepka, Susana

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Neto, Carlos de Moura

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DOI

10.5151/2594-5300-20335

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Abstract

Os tratamentos térmicos executados na liga 2024 foram de solubilização a 495°C, 505°C e 515°C e envelhecimento artificial nas temperaturas de 190°C e 208°C. Os valores mais elevados de resistência mecânica foram obtidos na liga solubilizada a 505°C e envelhecida a 208°C/2h. Esta condição foi escolhida para a execução dos ensaios de fadiga e levantamento da curva S-N. O corpo-de-prova suportou mais de 7,8x106 ciclos antes de romper para ciclo de tensão de 110,23 MPa. As superfícies de fratura dos corpos-de-prova submetidos a tensões elevadas e baixo número de ciclos mostraram basicamente precipitados e microcavidades, enquanto que nas fraturas dos corpos-de-prova submetidos a tensões baixas e elevado número de ciclos observou-se a presença de trincas ao longo de toda a borda da superfície de fratura.

A solution heat treatment in the alloy 2024 was performed at 495°C, 505°C and 515°C followed by quenching in water. After that, artificial aging was carried out at temperatures of 190°C and 208°C. Hardness measurements and tensile tests were performed to determine the mechanical properties of this material after heat treatments. Tensile and hardness tests revealed similar mechanical properties for the alloy in the three solution temperatures (495°C, 505°C and 515°C). The highest values of yield and ultimate strength were obtained in the solubilized alloy at 505°C and artificially aged at 208°C/2h. A cycle fatigue study on Al-2024 alloy was conducted under symmetric tension-compression at room temperature, using a flexion-rotation testing machine. S-N curve has not shown a typical fatigue limit, but a drop steadily with decreasing stress cycle. Specimen supported more than 7.8 x 106 cycles before break to a stress cycle of 110.23 MPa. The fracture surfaces of specimens submitted to high stress and low number of cycles showed mainly precipitates and microvoids, while the fractures of specimens submitted to low stress and high number of cycles was observed the presence of cracks along the periphery of the fracture surface.

Keywords

Al-Cu; precipitação; Envelhecimento; Fadiga.

Al-Cu; Precipitation; Aging; Fatigue.