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Na indĂșstria aeronĂĄutica, reduzir o peso das aeronaves e prolongar a vida Ăștil dos componentes Ă© essencial para a eficiĂȘncia e a segurança. O estudo de ligas leves, como alumĂnio e titĂąnio), a aplicação de tĂ©cnicas como o Shot Peening e o fabrico de componentes por Selective Laser Melting (SLM) constitui uma abordagem integrada para se alcançarem os objetivos atuais desta indĂșstria e promover a sustentabilidade, tornando estas vertentes de investigação particularmente relevantes para o setor. Na presente tese, estudou-se o efeito do Shot Peening, aplicado com equipamento automĂĄtico, em ligas leves de interesse industrial, a liga Al 7475-T7351 e a Ti-6Al-4V (obtida por SLM), com o propĂłsito de compreender as alteraçÔes microestruturais, de dureza e de rugosidade induzidas. No caso da liga Ti-6Al-4V, realizou-se um estudo dos defeitos intrĂnsecos ao SLM, bem como das suas fraturas. Para tal, foram realizados ensaios com recurso a microscopia Ăłtica, microscopia eletrĂłnica de varrimento, nanotomografia de raios-X, mediçÔes de rugosidade e microdurezas, bem como ensaios de tração. Da anĂĄlise de resultados das microdurezas, concluiu-se um aumento desta propriedade na zona mais superificial, diminuindo gradualmente em profundidade, em ambas as ligas. No caso da liga de Ti-6Al-4V, os valores de microdurezas foram superiores ao esperado, devido Ă formação de martensite αâ em grandes quantidades. A rugosidade aumentou em ambas as ligas, sendo mais acentuada no alumĂnio, refletindo que tem menor resistĂȘncia ao impacto das granalhas e Ă deformação plĂĄstica localizada. Em conclusĂŁo, verificaram-se os efeitos esperados da aplicação do Shot Peening. Pela anĂĄlise de defeitos, concluiu-se que existe necessidade de alteração dos parĂąmetros de produção de SLM, para os provetes de Ti-6Al-4V, nomeadamente da densidade de energia que deve ser aumentada. A qualidade dos pĂłs usados deve tambĂ©m ser uma prioridade. As superfĂcies de fratura revelaram um material dĂșctil. A presença de oxigĂ©nio nas mesmas indicou falhas na atmosfera inerte. Por Ășltimo, foi desenvolvido um modelo de previsĂŁo de vida Ă fadiga baseado nos resultados obtidos.
Abstract In the aeronautical industry, reducing the weight of aircraft and prolonging the service life of components is essential for efficiency and safety. The study of lightweight alloys (such as aluminium and titanium), the application of techniques like shot peening and the manufacturing of components using Selective Laser Melting (SLM) constitute an integrated approach to achieving the current objectives of this industry and promoting sustainability, making these research areas particularly relevant to the sector. In the present thesis, the effect of shot peening, applied using automated equipment, was studied in industrially relevant lightweight alloys, the Al 7475-T7351 alloy and the Ti-6Al-4V alloy (produced by SLM), with the aim of understanding the induced microstructural, microhardness and roughness changes. In the case of Ti-6Al-4V, intrinsic defects associated with its manufacturing process SLM, and their fracture behaviour were also investigated. For this purpose, tests were performed using optical microscopy, scanning electron microscopy, X-ray nanotomography, roughness and microhardness measurements, as well as tensile testing. Analysis of the microhardness results showed an increase in this property at the surface, gradually decreasing with depth in both alloys. For Ti-6Al-4V, the microhardness values exceeded the values present in bibliography, due to the extensive formation of 뱉 martensite. Surface roughness increased in both alloys, being more pronounced in aluminum, reflecting its lower resistance to shot impact and localized plastic deformation. Overall, the expected effects of Shot Peening were observed. Defect analysis indicated the need to adjust SLM production parameters for Ti-6Al-4V specimens, particularly by increasing the energy density. The quality of the powders used should also be a priority. Fracture surfaces revealed a ductile material, while the presence of oxygen indicated flaws in the inert atmosphere. Finally, a fatigue life prediction model was developed based on the obtained results.
Abstract In the aeronautical industry, reducing the weight of aircraft and prolonging the service life of components is essential for efficiency and safety. The study of lightweight alloys (such as aluminium and titanium), the application of techniques like shot peening and the manufacturing of components using Selective Laser Melting (SLM) constitute an integrated approach to achieving the current objectives of this industry and promoting sustainability, making these research areas particularly relevant to the sector. In the present thesis, the effect of shot peening, applied using automated equipment, was studied in industrially relevant lightweight alloys, the Al 7475-T7351 alloy and the Ti-6Al-4V alloy (produced by SLM), with the aim of understanding the induced microstructural, microhardness and roughness changes. In the case of Ti-6Al-4V, intrinsic defects associated with its manufacturing process SLM, and their fracture behaviour were also investigated. For this purpose, tests were performed using optical microscopy, scanning electron microscopy, X-ray nanotomography, roughness and microhardness measurements, as well as tensile testing. Analysis of the microhardness results showed an increase in this property at the surface, gradually decreasing with depth in both alloys. For Ti-6Al-4V, the microhardness values exceeded the values present in bibliography, due to the extensive formation of 뱉 martensite. Surface roughness increased in both alloys, being more pronounced in aluminum, reflecting its lower resistance to shot impact and localized plastic deformation. Overall, the expected effects of Shot Peening were observed. Defect analysis indicated the need to adjust SLM production parameters for Ti-6Al-4V specimens, particularly by increasing the energy density. The quality of the powders used should also be a priority. Fracture surfaces revealed a ductile material, while the presence of oxygen indicated flaws in the inert atmosphere. Finally, a fatigue life prediction model was developed based on the obtained results.
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Al 7475-T7351 Sective laser melting Shot peening Ti-6Al-4V