ANALYSIS OF PITTING CORROSION ON AN INCONEL 718 ALLOY SUBMITTED TO AGING HEAT TREATMENT
ANÁLISE DE CORROSÃO POR PITE NA LIGA INCONEL 718 SUBMETIDA A TRATAMENTO TÉRMICO DE ENVELHECIMENTO
Caliari, Felipe Rocha; Rosa, Elias Felipe da; Silva, Maria Auxiliadora da; Reis, Danieli Aparecida P.
http://dx.doi.org/10.4322/tmm.2014.028
Tecnol. Metal. Mater. Min., vol.11, n3, p.189-194, 2014
Abstract
Inconel 718 is one of the most important superalloys, and it is mainly used in the aerospace field on account of its high mechanical strength, good resistance to fatigue and creep, good corrosion resistance and ability to operate continuously at elevated temperatures. In this work the resistance to pitting corrosion of a superalloy, Inconel 718, is analyzed before and after double aging heat treatment. The used heat treatment increases the creep resistance of the alloy, which usually is used up to 0.6 Tm. Samples were subjected to pitting corrosion tests in chloride-containing aqueous solution, according to ASTM-F746-04 and the procedure described by Yashiro et al. The results of these trials show that after heat treatment the superalloy presents higher corrosion resistance, i.e., the pitting corrosion currents of the as received surfaces are about 6 (six) times bigger (~0.15 mA) than those of double aged surfaces (~0.025 mA).
Keywords
Double aging heat treatment, Pitting corrosion, Inconel 718.
Resumo
O Inconel 718 é uma das superligas mais importantes, sendo utilizada principalmente no setor aeroespacial devido a alta resistência mecânica, boa resistência a fadiga e fluência, boa resistência a corrosão e capaz de operar continuamente em temperaturas elevadas. Neste trabalho a resistência à corrosão por pite da superliga Inconel 718 é analisada antes e após o tratamento térmico de duplo envelhecimento. O tratamento térmico utilizado aumenta a resistência à fluência desta superliga, que normalmente é utilizada até 0,6 Tm. Amostras foram submetidas ao teste de corrosão por pite em solução de cloreto de sódio, de acordo com a norma ASTM-F746-04 e o procedimento descrito por Yashiro et al. Os resultados mostram que a superliga apresenta maior resistência a corrosão após o tratamento térmico, isto é, a corrente de corrosão por pite da condição como recebida é 6 vezes maior (~0,15mA) do que a envelhecida (~0,025 mA).
Palavras-chave
Duplo envelhecimento, Corrosão por pite, Inconel 718.
Referências
1. Sims TS, Stoloff N, Hagel WC. Superalloys II: high temperature materials for aerospace and industrial power. New York: John Willey; 1987.
2. Durand-Charre M. The microstructure of superalloys. Amsterdam: CRC Press; 1997.
3. Yashiro H, Tanno K, Koshiayama S, Akashi, K. Critical pitting potentials for type 304 stainless steel in hightemperature chloride solutions. Corrosion. 1996;52(2):109-114. http://dx.doi.org/10.5006/1.3292101
4. American Society for Testing Materials. ASTM F746-04: standard test method for pitting or crevice corrosion of metallic surgical implant materials. West Conshohocken; 2009.
5. American Society for Testing Materials. ASTM E112-96(2004)e2: standard test methods for determining average grain size. West Conshocken; 2004.
6. Caliari FR, Candioto KCG, Reis DAP, Couto AA, Moura Neto C, Nunes CA. Study of the mechanical behavior of an Inconel 718 aged superalloy submitted to hot tensile tests. Warrendale: SAE International; 2011. (SAE Technical Paper Series, 2011-36-0328, v. E). http://dx.doi.org/10.4271/2011-36-0328
7. Wlodek ST, Field RD. The effects of long time exposure on alloy 718. In: Loria EA, editor. Superalloys 718, 625, 706 and derivatives. Warrendale: TMS; 1994. p.659-670. http://dx.doi.org/10.7449/1994/Superalloys_1994_659_670
8. Chen T, John H, Xu J, Lu Q, Hawk J, Liu X. Influence of surface modifications on pitting corrosion behavior of nickel-base alloy 718. Part 2: effect of aging treatment. Corrosion Science. 2014;78:151-161. http://dx.doi.org/10.1016/j.corsci.2013.09.010
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