Correlação entre parâmetros térmicos de solidificação, microestrutura e dureza para uma liga Al5%Cu0,8%Mg antes e após o tratamento térmico T6
Correlation between thermal parameters of solidification, microstructure and hardness for an Al5%Cu0,8%Mg alloy before and after T6 heat treatment
Carlos Maranhão Piorski Júnior; Rafael Kakitani; Noé Cheung; Felipe Bertelli
Resumo
O objetivo deste trabalho foi realizar a solidificação da liga Al5%Cu0,8%Mg em peso com um aparato de solidificação direcional ascendente, a fim de determinar a correlação entre a taxa de resfriamento e os espaçamentos dendríticos primários - EDP (λ1 ) e a dureza Rockwell B antes e após um tratamento térmico de solubilização e precipitação. A partir de amostras com diferentes escalas microestruturais, foi analisado o efeito de um tratamento térmico (TT) artificial T6 e o efeito do λ1 na efetividade do TT. Técnicas de caracterização por microscopia óptica e eletrônica de varredura foram utilizadas e as microestruturas observadas mostram uma matriz dendrítica rica em Al (α-Al) e θ-(Al2 Cu), além de fases intermetálicas S (Al2 CuMg) dentro das regiões interdendríticas. A maior dureza foi observada sempre para estruturas mais refinadas, mesmo após o envelhecimento da liga. O tempo médio de tratamento ideal para obtenção dos maiores valores de dureza ficou entre 2 e 3 horas de precipitação. Os percentuais de dureza aumentaram em torno de 11% no ponto máximo, com valores de 62-70 HRB para os λ1 s analisados.
Palavras-chave
Abstract
The aim of this paper was to investigate the solidification of Al5%Cu0.8%Mg alloy using an upward directional solidification apparatus. The study aimed to explore the relationship between cooling rate, primary dendritic spacings (λ1 ), and Rockwell B hardness, both before and after solubilization and precipitation heat treatment. By examining samples with varying microstructural scales, the effect of a T6 artificial heat treatment (TT) and the influence of λ1 on the treatment’s effectiveness were analyzed. Optical and scanning electron microscopy were employed to characterize the microstructures, which revealed a dendritic matrix rich in α-Al and θ-(Al2 Cu), as well as intermetallic phases S (Al2 CuMg) in the interdendritic regions. The results indicated that higher hardness was consistently associated with more refined microstructures, even after aging. The optimal treatment duration for achieving the highest hardness values was between 2 and 3 hours of precipitation. Hardness improved by approximately 11% at its peak, with Rockwell C hardness values ranging from 62 to 70 for the analyzed λ1 spacings.
Keywords
References
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Submitted date:
02/13/2024
Accepted date:
10/04/2024
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