Efeito da Diluição Sobre a Microestrutura da Liga AWS ER NiCrMo-14 na Soldagem de Revestimentos pelo Processo TIG com Alimentação de Arame Frio

Abstract

Este é um artigo publicado em acesso aberto (Open Access) sob a licença Creative Commons Attribution Non-Commercial, que permite uso, distribuição e reprodução em qualquer meio, sem restrições desde que sem fins comerciais e que o trabalho original seja corretamente citado. Effect of Dilution on the Microstructure of AWS ER NiCrMo-14 Weld Overlay Deposited by TIG Cold Wire Feed ProcessAbstract: The dilution is an event that have a high influence on the microstructure and, consequently, in the properties of weld claddings. The present study evaluated the effect of dilution level on the microstructure of the fusion zone of alloy Inconel 686 weld claddings. The claddings were welded by the TIG cold wire feed process. The dilution was calculated from the geometric characteristics and based on chemical composition of the materials obtained by energy dispersive X-ray spectroscopy and optical emission spectroscopy. The microstructure of all claddings were composed by a γ-FCC matrix with some minor precipitates. These particles are called in literature as topologically closed-packed phases (TCP). These precipitates assumed several morphological aspects, being the shapeless morphology observed in more frequency in all claddings evaluated, independent of dilution level. A phase with lamellar morphology, which growth establishing an orientation relationship with the γ-FCC matrix solidification direction, was observed only in claddings with a low dilution level. In addition, a shapeless phase with a fine precipitation aggregated was observed in claddings with a high dilution level.Key-words: TIG; Nickel alloy; Inconel 686; Dilution; Microstructure. IntroduçãoA liga Inconel 686 pertence ao grupo das superligas de níquel e destaca-se pela elevada resistência à corrosão localizada. Isto se deve à elevada concentração dos elementos Cr, Mo e W, que são responsáveis por manter a integridade da liga mesmo em ambientes de elevada agressividade corrosiva. É uma liga pertencente à terceira geração das superligas de níquel e foi desenvolvida em 1992 para suprir a necessidade de aplicações, as quais requeriam elevada resistência à corrosão, já que as principais superligas anteriormente utilizadas (ligas 625, C-276 e C-22) não atendiam às severas condições de serviço [1]. Por esse motivo, a liga Inconel 686 vem sendo utilizada em aplicações nas indústrias do petróleo e gás, onde é comum que os seus equipamentos e componentes estejam operando nas mais adversas condições de serviço (altas temperaturas, elevada pressão, fluidos corrosivos, etc.).

Electron detection modes comparison for quantification of secondary phases of Inconel 686 weld metal

“…Studies revealed the stronger dependence of the interaction volume on the accelerating voltage and the chemical composition of the specimen [33,34]. In addition, according to the literature, the secondary phases observed in nickel-based alloys are known as topologically closed packages (TCP) [6,[12][13][14]16,19]. These phases show a complex chemical stoichiometry, which can be tetragonal (σ-phase: Cr 0.99 Fe 1.01 ) [35], rhombohedral (μphase: Co 6 Mo 7 ) [36] and orthorhombic (P-phase: Cr 9 Mo 21 Ni 20 ) [37].…”

“…On the other hand, nanometric phases observed in aluminum alloys, for example, require transmission electron microscopy (TEM) or atomic force microscopy (AFM) [18]. In terms of quantitative analyses of the secondary phases observed in the weld microstructure of nickel-based alloys, scanning electron microscopy (SEM) has been shown a good option, because the particles have dimensions of some microns [19].…”