EFEITO DA SOLUBILIZAÇÃO E ENVELHECIMENTO NA MICROESTRUTURA E RESISTÊNCIA A CORROSÃO DA LIGA DE MAGNÉSIO AZ31
COMPARATIVE BEHAVIOR OF MAGNESIUM ALLOY AZ31 BY CYCLIC POLARIZATION TEST
Camila Queiroz Correia Fernandes, José Adilson de Castro, Elivelton Alves Ferreira, Darlene Souza da Silva Almeida, Leonardo Martins da Silva
Resumo
Este trabalho apresenta um estudo comparativo da resistência a corrosão da liga de magnésio AZ31 tratada termicamente por solubilização e diferentes tempos de envelhecimento, submetida ao teste de polarização cíclica em solução de 3,5% de NaCl. Amostras da liga foram solubilizadas a 440 °C por 24 horas. Após a solubilização três amostras foram envelhecidas a 220 °C; por 2, 6 e 12 horas, respectivamente. Foram realizadas análises microestruturais com a finalidade de compreender as alterações microestruturais advindas dos tratamentos térmicos realizados. As amostras foram submetidas ao ensaio de polarização cíclica com a finalidade de correlacionar o efeito das mudanças alcançadas pelos tratamentos térmicos na resistência à corrosão da liga de magnésio AZ31. O comportamento das curvas de polarização cíclica foi semelhante para todas as amostras, sugerindo tendência a corrosão por pite. Não houve variação significativa nos valores de potencial de corrosão, sugerindo que os tratamentos térmicos aplicados não influenciaram a resistência a corrosão da liga.
Palavras-chave
Abstract
This work presents a comparative study between the corrosion resistance of the magnesium alloy AZ31 treated by solubilization and aging at different times, submitted to the cyclic polarization test in 3.5% NaCl solution. Four samples were solubilized at 440 °C for 24 hours. After solubilization, three samples were aged at 220 °C; one for 2 hours, another for 6 hours and a third for 12 hours. Microstructural analysis were carried out to identify microstructural changes obtained. The samples were submitted to the cyclic polarization test in order to correlate the effect of the changes achieved by heat treatments on the corrosion resistance of the magnesium alloy AZ31. The cyclic polarization presents curves with similar behavior for the samples, indicating propensity to pitting corrosion. There were no significant variation in the values of corrosion potential, suggesting that the heat treatments applied did not influenced the corrosion resistance of the alloy.
Keywords
Referências
2 Revie RW. Uhlig’s corrosion handbook. 2nd ed. New York: John Wiley & Sons, Inc.; 2000.
3 Cao FH, Len VH, Zhang Z, Zhang VH, Zhang X. Corrosion behavior of magnesium and its alloy in NaCl solution. Russian Journal of Electrochemistry. 2007 [acesso em 12 dec. 2018];43:837-843. Disponível em: https://link.springer.com/article/10.1134/S1023193507070142.
4 Chang YL, Qin TW, Wang HM, Zhang Z, editors. Comparison of corrosion behaviors of AZ31, AZ91, AM60 and ZK60 magnesium alloys. Transactions of Nonferrous Metals Society of China. 2009 [acesso em 12 dec. 2018]: 19:517-524. Disponível em: www.sciencedirect.com/science/article/abs/pii/S1003632608603052.
5 Agarwal S, Curtin J, Duffy B, Jaiswa LS. Biodegradable magnesium alloys for orthopaedic applications: A review on corrosion, biocompatibility and surface modifications. Materials Science and Engineering C. 2016 [acesso em 13 dec. 2018];68:948-963. Disponível em: https://www.sciencedirect.com/science/article/pii/S0079642517300506.
6 Esmaily M, Svensson JE, Fajardo S, Birbilis N, Frankel GS, Virtanen S, et al. Fundamentals and advances in magnesium alloy corrosion. Progress in Materials Science. 2017 [acesso em 13 dec. 2018];89:92-193. Disponível em: https://www.sciencedirect.com/science/article/pii/S0079642517300506.
7 Tan L, Dong J, Chen J, Yang K. Development of magnesium alloys for biomedical applications: structure, process to property relationship. Materials Technology. 2018 [acesso em 13 dec. 2018];33:235-243. http://dx.doi.org/10.1080/10667857.2017.1405890.
8 Ghoneim AA, Fekry AM, Ameer MA. Electrochemical behavior of magnesium alloys as biodegradable materials in Hank’s solution. Electrochimica Acta. 2010 [acesso em 13 dec. 2018];55:6028-6035. Disponível em: https://www.sciencedirect.com/science/article/pii/S001346861000753X
9 Pinela VM, Oliveira LA, Oliveira MCL, Antunes RA. Study of the Corrosion Process of AZ91D Magnesium Alloy during the First Hours of Immersion in 3.5 wt.% NaCl Solution. International Journal of Corrosion. 2018 [acesso em 13 dec. 2018];2018. Disponível em: https://www.hindawi.com/journals/ijc/2018/8785154/
10 Wan D, Wang J, Wang G, Lin L, Feng Z, Yang G. Precipitation and responding damping behavior of heat-treated AZ31 magnesium alloy. Chin Shu Hsueh Pao. 2009 [acesso em 12 dec. 2018];22:1-6. Disponível em: https://www.sciencedirect.com/science/article/pii/S1006719108600630.
11 Tsao LC. Stress-corrosion cracking susceptibility of AZ31 alloy after varied heat-treatment in 3.5 wt.% NaCl solution. International Journal of Materials Research. 2010 [acesso em 12 dec. 2018];101:9. Disponível em: https://www.hanser-elibrary.com/doi/abs/10.3139/146.110394.
12 American Society for Testing and Materials. ASTM G102 – 89: Standard practice for calculation of corrosion rate and related information from eletrochemical measurements. ASTM International: West Conshohocken
13 Singh IB, Singh M, Das S. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5%. J. Magnesium Alloy. 2015 [acesso em 12 dec. 2018];3:141-147. Disponível em: https://www.sciencedirect.com/science/article/pii/S221395671500016X.
14 Stráskáa J, Janečeka M, Čížekb J, Stráskýa J, Hadzima B. Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP). Materials Characterization. 2014 [acesso em 12 dec. 2018];94:69-79. Disponível em: https://www.sciencedirect.com/science/article/pii/S1044580314001570.
15 ASM Handbook committee. Alloy Phase Diagrams, ASM International, 2016.
16 Wang C, Deng K, Nie K, Shang S, Liang W. Competition behavior of the strengthening effects in as-extruded AZ91 matrix: Influence of pre-existed Mg17Al12 phase. Materials Science and Engineering A. 2016 [acesso em 12 dec. 2018];A656:102-110. Disponível em: https://www.sciencedirect.com/science/article/abs/pii/S0921509316300235.
17 Song GL, Atrens A, Dargusch M. Influence of microstructure on the corrosion of diecast AZ91D. Corrosion Science. 1999 [acesso em 12 dec. 2018];41:249-273. Disponível em: https://www.sciencedirect.com/science/article/pii/S0010938X98001218.
18 Kleiner S, Uggowitzer PJ. Mechanical Anisotropy of Extruded Mg - 6% Al - 1% Zn Alloy. Materials Science and Engineering A. 2004 [acesso em 12 dec. 2018];379:258-263. Disponível em: https://www.sciencedirect.com/science/article/abs/pii/S0921509304001893
Facebook
Google+
Twitter
LinkedIn
Mendeley
StumbleUpon
CiteULike
Reddit
Email