MIGRAÇÃO DE MOLIBDÊNIO NA INTERFACE MATRIZ/PRECIPITADO EM METAIS DE SOLDA DE LIGAS Ni-Cr-Mo
MIGRATION OF MOLIBDENUM ON MATRIX/PRECIPITATE INTERFACE IN Ni-Cr-Mo WELD METALS
Silva, Cleiton Carvalho; Afonso, Conrado Ramos M.; Miranda, Helio Cordeiro de; Ramirez, Antonio Jose; Farias, Jesualdo Pereira
http://dx.doi.org/10.4322/tmm.2011.031
Tecnol. Metal. Mater. Min., vol.8, n3, p.197-202, 2011
Resumo
O presente trabalho avalia a migração de elementos químicos, especialmente o molibdênio, na interface matriz/precipitado de revestimentos de ligas Ni-Cr-Mo-W, depositados sobre substrato de aço C-Mn. A caracterização microestrutural foi realizada empregando-se as técnicas de microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET) e espectroscopia de energia dispersiva de raios X (EDS). Indícios de empobrecimento de molibdênio ao redor das fases secundárias são observados nas análises por MEV. Tais fases foram identificadas por MET como fase P. Análises de MET/EDS confirmam haver uma migração de molibdênio da matriz em direção aos precipitados. Comportamento semelhante é observado para o tungstênio. O fenômeno de migração de molibdênio e tungstênio é observado em cordões de solda que foram reaquecidos devido aos inúmeros ciclos térmicos de soldagem para a formação da camada de revestimento.
Palavras-chave
Migração, Molibdênio, Superligas, Metal de solda
Abstract
This work evaluates the chemistry elements distribution on matrix/precipitate interface in a Ni-Cr-Mo-W alloy weld metals deposited on substrate of C-Mn steel. Microestructural characterization was carried out through optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The results have shown that the presence of secondary phases precipitates in the interdendritic region. Through SEM analysis indications of migration of molybdenum around these phases are observed. These precipitates are identified as P-phase by TEM analysis. The molybdenum migration along matrix/precipitate interface is confirmed through EDS. The phenomenon of molybdenum migration is a result of a re-heating due to several welding heat cycles deposited to promote the coating layer.
Keywords
Migration, Molybdenum, Superalloys, Weld metal
Referências
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17 El-DASHER, B. S.; EDGECUMBE T. S.; TORRES S. G. The effect of solution annealing on the microstructural behavior of alloy 22 welds. Metallurgical and Materials Transactions A. v. 37, n. 3, p. 1027-38, Mar. 2006.
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19 GE, B.; LI, Y. J.; ZHU J. Study of g/γ´ interfaces in nickel-based, single-crystal superalloys by scanning transmission electron microscopy. Metallurgical and Materials Transactions A, v. 42, n. 3, p. 548-52, Mar. 2011.
20 HEUBNER, U.L. et al. Electrochemical behavior and its relation to composition and sensitization of NiCrMo alloys in ASTM G-28 solution. Corrosion, v. 45, n. 3, p. 249-59, Mar. 1989.
21 GORHE, D. D. et al. Electrochemical methods to detect susceptibility of Ni-Cr-Mo-W alloy 22 to intergranular corrosion. Metallurgical and Materials Transactions A, v. 36, n. 5, p. 1153-67, May 2005.
22 GORHE, D. D. et al. Development of an electrochemical reactivation test procedure for detecting microstructural heterogeneity in Ni-Cr-Mo-W alloy welds. Journal of Materials Science, v. 39, n. 6, p. 2257-61, Mar. 2004.
2 CARRANZA, R. M. et al. Corrosion behavior of alloy 22 in chloride solutions containing organic acids. In: CORROSION 2006, San Diego. Proceedings… Houston: NACE International, 2006. Paper 06627.
3 DEACON, R. M.; DUPONT, J. N.; MARDER, A. R. High temperature corrosion resistance of candidate nickel-based weld overlay alloys in a low NOx environment. Materials Science and Engineering A, v. 460-461, p. 392-402, 2007.
4 RAJESWARI, S. et al. Surface characterization and pitting behavior of high-Cr-Ni-Mo alloys in simulated white water environment. Corrosion, v. 57, n. 5, p. 465-75, May 2001.
5 YIN, Z. F. et al. Electrochemical behaviour of Ni-base alloys exposed under oil/gas field environments. Corrosion Science, v. 51, n. 8, p. 1702-6, Aug. 2009.
6 JONES, D. A. Principles and prevention of corrosion. 2. ed. Upper Saddle River: Prentice-Hall, 1996.
7 PIERAGGI, B.; MACDOUGALL, B.; RAPP, R. A. The role of the metal/oxide interface in the growth of passive films in aqueous environments. Corrosion Science, v. 47, n. 1, p. 247-56, Jan. 2005.
8 OLEFJORD, I.; WEGRELIUS, L. Surface analysis of passive state. Corrosion Science. v. 31, p. 89-98, Sep. 1990.
9 SCHNEIDER, A. et al. AES analysis of pits and passive films formed on Fe-Cr, Fe-Mo and Fe-Cr-Mo alloys. Corrosion Science. v. 31, p. 191-6, Sep. 1990.
10 SILVA, C. C.; FARIAS, J. P.; SANT’ANA, H. B. Evaluation of AISI 316L stainless steel welded plates in heavy petroleum environment. Materials and Design, v. 30, n. 5, p. 1581-7, May 2009.
11 SILVA, C. C. et al. Avaliação da corrosão do metal de solda de eletrodos revestidos AWS E309MoL-16 em meio contendo petróleo pesado. Tecnologia em Metalurgia e Materiais. v. 2, n. 3, p. 37-42, jul.-set. 2006.
12 SOURMAIL, T.; TOO, C. H.; BHADESHIA, H. K. D. H. Sensitisation and Evolution of Chromium-depleted Zones in Fe–Cr–Ni–C Systems. ISIJ International, v. 43, n. 11, p. 1814-20, Nov. 2003.
13 LEE, H. T.; WU, J. L. The effects of peak temperature and cooling rate on the susceptibility to intergranular corrosion of alloy 690 by laser beam and gas tungsten arc welding. Corrosion Science, v. 51, n. 3, p. 439-45, Mar. 2009.
14 CIESLAK, M. J.; HEADLEY, T. J.; ROMIG JR., A. D. The welding metallurgy of hastelloy alloys C-4, C-22, and C-276. Metallurgical and Materials Transactions A, v. 17, n. 11, p. 2035-46, Nov. 1986.
15 CIESLAK, M. J. et al. The use of new PHACOMP in understanding the solidification microstructure of nickel base alloy weld metal. Metallurgical and Materials Transactions A, v. 17, n. 12, p. 2107-16, Dec. 1986.
16 RAGHAVAN, M.; BERKOWITZ, B. J.; SCANLON, J. C. Electron microscopic analysis of heterogeneous precipitates in hastelloy C-276. Metallurgical and Materials Transactions A, v. 13, n. 6, p. 979-84, Jun. 1982.
17 El-DASHER, B. S.; EDGECUMBE T. S.; TORRES S. G. The effect of solution annealing on the microstructural behavior of alloy 22 welds. Metallurgical and Materials Transactions A. v. 37, n. 3, p. 1027-38, Mar. 2006.
18 SUMMERS, T. S. E. et al. Influence of Thermal Aging on the Mechanical and Corrosion Properties of GTAW welds of Alloy N06022. In: SCIENTIFIC BASIS FOR NUCLEAR WASTE MANAGEMENT, 25., 2002. Proceedings… Warrendale, PA: Materials Research Society, 2002. v. 713, p. 45-52.
19 GE, B.; LI, Y. J.; ZHU J. Study of g/γ´ interfaces in nickel-based, single-crystal superalloys by scanning transmission electron microscopy. Metallurgical and Materials Transactions A, v. 42, n. 3, p. 548-52, Mar. 2011.
20 HEUBNER, U.L. et al. Electrochemical behavior and its relation to composition and sensitization of NiCrMo alloys in ASTM G-28 solution. Corrosion, v. 45, n. 3, p. 249-59, Mar. 1989.
21 GORHE, D. D. et al. Electrochemical methods to detect susceptibility of Ni-Cr-Mo-W alloy 22 to intergranular corrosion. Metallurgical and Materials Transactions A, v. 36, n. 5, p. 1153-67, May 2005.
22 GORHE, D. D. et al. Development of an electrochemical reactivation test procedure for detecting microstructural heterogeneity in Ni-Cr-Mo-W alloy welds. Journal of Materials Science, v. 39, n. 6, p. 2257-61, Mar. 2004.
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