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Otimização dos parâmetros de impressão e caracterização mecânica da liga Cu10Al por Selective Laser Melting
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Abstract(s)
O fabrico aditivo, comumente conhecido como “impressão 3D”, consiste numa das maiores
inovações tecnológicas do século XX que atrai uma série de vantagens para diversos setores
industriais. Este processo de fabrico é baseado na adição sequencial de camadas de material, o
que afasta a necessidade de moldes e outras ferramentas específicas, e permite a produção de
componentes geometricamente complexos com o menor desperdício de recursos possível.
Entre todas as tecnologias de fabrico associadas a este processo, o selective laser melting
destaca-se pela capacidade de produzir peças metálicas com elevada massa volúmica relativa e
propriedades mecânicas, muitas das vezes semelhantes ou superiores às obtidas por processos
convencionais de fabrico. No entanto, o processamento de ligas que envolvem o cobre como
material de base enfrentam desafios adicionais decorrentes da elevada condutividade térmica
e baixa absorbância à radiação laser típica dos equipamento de impressão, o que condiciona o
desenvolvimento de novas soluções mais eficientes para a indústria através deste processo.
Neste contexto, optou-se por se investigar um bronze de alumínio, Cu10Al, com baixa
representatividade científica e potencial de integrar diversas aplicações que beneficiam das
excelentes propriedades de condução térmica e elétrica. Portanto, esta dissertação visou a
otimização dos parâmetros de impressão, não só para conferir elevada qualidade metalúrgica
e elevadas propriedades mecânicas, como também maximizar a eficiência produtiva, através
do estudo da influência da velocidade de varrimento. A seleção criteriosa dos parâmetros
ótimos de processamento foi obtida através da análise de propriedades como a massa volúmica
relativa dos provetes, o tempo de impressão por unidade de volume e a dureza para as
condições com e sem o tratamento térmico de têmpera selecionado. Para além disso, provetes
impressos com os parâmetros otimizados foram caracterizado à tração e à fratura. A
combinação de parâmetros ótimos, que resultam numa densidade volumétrica de energia de
67 J/mm3, permitiu a obtenção de provetes com 98,61% de massa volúmica relativa e a redução
do tempo de impressão por unidade de volume de 15,38 para 6,894 min/cm3, que corresponde
a uma redução de 55% em relação aos parâmetros de referência considerados. Já os valores de
dureza, obtidos para ambas as condições, tal como fabricados e submetidos ao tratamento
térmico, correspondem a 235,0 HV e 159,5 HV, respetivamente. A aplicação do tratamento
térmico à liga estudada demostrou um incremento significativo na ductilidade do material em
cerca de 300%, passando dos 5 para os 20% de deformação na rotura, em detrimento da sua
resistência mecânica e rigidez. Apesar de não ter sido possível apresentar valores válidos para
o fator de intensidade de tensão crítico, devido à falha em garantir o estado plano de
deformação ao longo do ensaio, foi possível obter um valor de tenacidade à fratura condicional
para a liga de Cu10Al, processada com 67 J/mm3 sem tratamento térmico, de 43,8 MPa.√m.
Additive manufacturing, commonly known as “3D printing”, is one of the most significant technological innovations of the 20th century, offering numerous advantages across a wide range of industrial sectors. This manufacturing process is based on the sequential addition of material layers, which eliminates the need for moulds and other specific tools, and allows the production of components with highly complex geometries while minimizing resource waste. Among all additive manufacturing technologies, selective laser melting stands out for its ability to produce metallic parts with high relative density and mechanical properties, often comparable to or even exceeding those achieved through conventional manufacturing processes. However, processing copper-based alloys faces additional challenges due to their high thermal conductivity and low absorptivity of typical laser radiation, which limits the development of more efficient solutions for industrial applications through this process. In this context, this work focuses on the study of an aluminium bronze alloy, Cu10Al, which has limited scientific coverage but with strong potential for applications requiring excellent thermal and electrical conductivity. Therefore, this dissertation aimed to optimize the printing parameters, not only to provide high metallurgical quality and high mechanical properties, but also to maximize production efficiency, through the study of the influence of scanning speed. The optimal processing parameters were selected through a multi-criteria analysis considering the specimens’ relative density, build time per unit volume and hardness values in both as built and heat-treated conditions (quenching). In addition, specimens produced under the optimized parameters were characterized by tensile and fracture testing. The combination of the optimal parameters, which results in a volumetric energy density of 67 J/mm3, allowed obtaining specimens with 98.61% of relative density and reducing the printing time per unit volume from 15.38 to 6.894 min/cm3, which corresponds to a reduction of 55% in relation to the considered reference parameters. The hardness values obtained for both conditions, as build and subjected to the heat treatment, correspond to 235,0 and 159,5 HV, respectively. The application of the heat treatment to the studied alloy demonstrated a significant increase in the ductility of the material by approximately 300%, increasing from 5 to 20% of deformation at break, to the detriment of its mechanical strength and rigidity. Although it was not possible to present valid result for the critical stress intensity factor, due to the failure to guarantee the plane deformation state throughout the test, it was possible to obtain a conditional fracture toughness value for the Cu10Al alloy, processed with 67 J/mm3 without heat treatment, of 43,8 MPa.√m.
Additive manufacturing, commonly known as “3D printing”, is one of the most significant technological innovations of the 20th century, offering numerous advantages across a wide range of industrial sectors. This manufacturing process is based on the sequential addition of material layers, which eliminates the need for moulds and other specific tools, and allows the production of components with highly complex geometries while minimizing resource waste. Among all additive manufacturing technologies, selective laser melting stands out for its ability to produce metallic parts with high relative density and mechanical properties, often comparable to or even exceeding those achieved through conventional manufacturing processes. However, processing copper-based alloys faces additional challenges due to their high thermal conductivity and low absorptivity of typical laser radiation, which limits the development of more efficient solutions for industrial applications through this process. In this context, this work focuses on the study of an aluminium bronze alloy, Cu10Al, which has limited scientific coverage but with strong potential for applications requiring excellent thermal and electrical conductivity. Therefore, this dissertation aimed to optimize the printing parameters, not only to provide high metallurgical quality and high mechanical properties, but also to maximize production efficiency, through the study of the influence of scanning speed. The optimal processing parameters were selected through a multi-criteria analysis considering the specimens’ relative density, build time per unit volume and hardness values in both as built and heat-treated conditions (quenching). In addition, specimens produced under the optimized parameters were characterized by tensile and fracture testing. The combination of the optimal parameters, which results in a volumetric energy density of 67 J/mm3, allowed obtaining specimens with 98.61% of relative density and reducing the printing time per unit volume from 15.38 to 6.894 min/cm3, which corresponds to a reduction of 55% in relation to the considered reference parameters. The hardness values obtained for both conditions, as build and subjected to the heat treatment, correspond to 235,0 and 159,5 HV, respectively. The application of the heat treatment to the studied alloy demonstrated a significant increase in the ductility of the material by approximately 300%, increasing from 5 to 20% of deformation at break, to the detriment of its mechanical strength and rigidity. Although it was not possible to present valid result for the critical stress intensity factor, due to the failure to guarantee the plane deformation state throughout the test, it was possible to obtain a conditional fracture toughness value for the Cu10Al alloy, processed with 67 J/mm3 without heat treatment, of 43,8 MPa.√m.
Description
Keywords
Additive manufacturing Selective laser melting Printing parameters Productive efficiency Aluminium bronzes Mechanical properties Fabrico aditivo Parâmetros de impressão Eficiência produtiva Bronzes de alumínio Propriedades mecânicas