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
Referências
1 Davis JR. Aluminium and aluminium alloys. 6th ed. Ohio: ASM International; 2007. 784 p.
2 Hunsicker HY. Metallurgy of heat treatment and general principles of precipitation hardening. In: American Society for Metals, editor. Aluminium: properties and physical metallurgy. Materials Park, OH: ASM International; 1984. p. 152-157.
3 Barros A, Cruz C, Silva AP, Cheung N, Garcia A, Rocha O, et al. Length scale of solidification microstructure tailoring corrosion resistance and microhardness in T6 heat treatment of an Al–Cu–Mg alloy. Corrosion Engineering, Science and Technology. 2020;55(6):471-479. http://doi.org/10.1080/1478422X.2020.1742410.
4 Li S, Zhang J, Yang J, Deng Y, Zhang X. Influence of Mg contents on aging precipitation behavior of Al–3.5 Cu– xMg Alloy. Acta Metallurgica Sinica. 2014;27(1):107-114.
5 Chen Z-T, Lin F, Li J, Wang F, Meng Q-S. Diffusion bonding between AZ31 magnesium alloy and 7075 aluminum alloy. Applied Mechanics and Materials. 2014;618:150-153. http://doi.org/10.4028/www.scientific.net/ AMM.618.150.
6 Hsiao T-J, Chiu P-H, Tai C-L, Tsao T-C, Tseng C-Y, Lin Y-X, et al. Effect of Cu additions on the evolution of Eta-prime precipitates in Aged AA 7075 Al–Zn–Mg–Cu alloys. Metals. 2022;12(12):2120. http://doi.org/10.3390/ met12122120.
7 Ralston KD, Birbilis N, Weyland M, Hutchinson CR. The effect of precipitate size on the yield strength-pitting corrosion correlation in Al–Cu–Mg alloys. Acta Materialia. 2010;58(18):5941-5948. http://doi.org/10.1016/j. actamat.2010.07.010.
8 Garcia A. Solidificação: fundamentos e aplicações. 2ª ed. São Paulo: Universidade Estadual de Campinas; 2007.
9 Chen R, Xu Q, Guo H, Xia Z, Wu Q, Liu B. Correlation of solidification microstructure refining scale, Mg composition and heat treatment conditions with mechanical properties in Al-7Si-Mg cast aluminum alloys. Materials Science and Engineering A. 2017;685:391-402. http://doi.org/10.1016/j.msea.2016.12.051.
10 Thermo-Calc Software [página da internet]. 2019 [acesso em 1 mar. 2024]. Disponível em: www.thermocalc.com
11 Gündüz M, Çadirli E. Directional solidification of aluminium-copper alloys. Materials Science and Engineering A. 2002;327(2):167-185. http://doi.org/10.1016/S0921-5093(01)01649-5.
12 American Society for Testing and Materials. ASTM E18-22: standard test methods for rockwell hardness of metallic materials. West Conshohocken: ASTM; 2022.
13 Zuiko I, Kaibyshev R. Aging behavior of an Al–Cu–Mg alloy. Journal of Alloys and Compounds. 2018;759:108- 119. http://doi.org/10.1016/j.jallcom.2018.05.053.
14 Quan G, Ren L, Zhou M. Solutionizing and age hardening of aluminum alloys. Comprehensive Materials Finishing. 2017;2(2):372-397. http://doi.org/10.1016/B978-0-12-803581-8.09195-5.
15 Sunde JK, Johnstone DN, Wenner S, van Helvoort AT, Midgley PA, Holmestad R. Crystallographic relationships of T-/S-phase aggregates in an Al–Cu–Mg–Ag alloy. Acta Materialia. 2019;166:587-596. http://doi.org/10.1016/j. actamat.2018.12.036.
16 Barros A, Cruz C, Silva AP, Cheung N, Garcia A, Rocha O, et al. Length scale of solidification microstructure tailoring corrosion resistance and microhardness in T6 heat treatment of an Al–Cu–Mg alloy. Corrosion Engineering, Science and Technology. 2020;55(6):471-479. http://doi.org/10.1080/1478422X.2020.1742410.
Submetido em:
13/02/2024
Aceito em:
04/10/2024
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