Solidification of an alloy 625 weld overlay

DuPont, J. N.

doi:10.1007/bf02595452

Cited by 168 publications

(87 citation statements)

References 10 publications

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“…The Laves phase exhibits a hexagonal crystal structure and is characterized by A 2 B stoichiometric composition, where A stands for Ni, Fe and Cr, while B stands for Nb, Mo, Ti and Si. It is worth noting that the results acquired in the present study are consistent with the results presented by DuPont [2,[14][15][16], Silva [17] and Maguire [21]. It was also found that precipitates in the shape of a parallelogram contain much more Ti than the formerly discussed elongated precipitations.…”

Section: Resultssupporting

confidence: 92%

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Microsegregation and Precipitates in Inconel 625 Arc Weld Overlay Coatings on Boiler Pipes / Mikrosegregacja I Wydzielenia W Powłokach Ze Stopu Inconel 625 Napawanych Łukowo Na Rury Kotłowe

Rozmus-Górnikowska¹,

Blicharski²

2015

Archives of Metallurgy and Materials

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IntroductionResistance to corrosion is the decisive criterion for the selection of materials for construction of boiler elements for burning municipal and industrial waste due to the extremely aggressive environment of their operation. Therefore, boiler elements that operate in the most aggressive environments are usually subjected to weld overlaying with Ni alloys, in order to ensure the required operational life of boilers. The solidsolution strengthened nickel alloy Inconel 625 is widely used for welded coatings for these processes, as it is characterized by very good resistance to corrosion as well as good strength and weldability. Chromium is the element that enhances resistance to corrosion, especially in an oxidizing atmosphere. Therefore, it is the basic element of the 625 alloy. Moreover, Cr and especially Mo and Nb, provide solid-solution strengthening of the alloy [1,2].Weld overlaying is a process of depositing a material onto a product surface by welding methods [3]. Welded coatings have a structure typical to cast metals, characterized by the fact The aim of this work was to investigate the microsegregation and precipitates formed due to segregation in Inconel 625 arc weld overlay coatings on boiler pipes. Examination of microsegregation and precipitates were carried out by means of a scanning electron microscope (SEM) equipped with an EDS detector as well as a transmission electron microscope (TEM) equipped with a HAADF (STEM) and an EDS detectors. The presence of precipitations in the weld overlay was also confirmed with X-ray diffraction analysis (XRD) of residue in the form of powder that remained after the electrolytic dissolution of weld overlay matrix.The investigations showed that the interdendritic regions were considerably enriched during microsegregation with Nb, and less so with Mo. The distribution of Cr and Fe in the weld overlay is relatively uniform. The value of the partition coefficient k for Mo and Nb is lower than 1. Therefore, these elements segregate during solidification into the liquid and, once solidification is finished, the interdendritic regions are considerably enriched with these elements. The value of k for Cr, Ni and Fe are only slightly higher than 1. Though the Inconel 625 is a solid-solution strengthened alloy, precipitation of secondary phases occurs in weld overlays. Precipitations were identified as a Laves phase and carbonitrides (Nb, Ti)(C, N).

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Section: Resultssupporting

confidence: 92%

“…The distribution of Cr and Fe in the weld overlay was relatively uniform. Similar distribution of elements in an Inconel 625 weld overlay were obtained by Cieslak [11][12][13], DuPont [14][15][16] and Silva [17]. The lighter regions on the Nb and Mo distribution maps (SEM/EDS) correspond to interdendritic regions enriched with Mo and Nb (Fig.…”

Section: Resultssupporting

confidence: 78%

Microsegregation and Precipitates in Inconel 625 Arc Weld Overlay Coatings on Boiler Pipes / Mikrosegregacja I Wydzielenia W Powłokach Ze Stopu Inconel 625 Napawanych Łukowo Na Rury Kotłowe

Rozmus-Górnikowska¹,

Blicharski²

2015

Archives of Metallurgy and Materials

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“…Such elements like Nb, Mo, Si, and C have a high tendency to segregation [1,9,10]. They are pushed into the liquid during solidification, more and more enriching it.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Phase Transformations in Inconel 625 Alloy during Annealing

2016

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The investigation focused on the characterization of the microstructure and chemical composition changes after annealing. The research was conducted on the Inconel 625 weld overlay deposited on a boiler steel. The annealing was performed for 10 h at temperatures from 600 to 1000• C. The microstructure and chemical composition were examined by scanning electron microscope and transmission electron microscope equipped with an energy dispersive X-ray spectrometer. Weld overlays were produced by an innovative method of cold metal transfer.

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“…Em soldas, a evolução da microestrutura na zona de fusão de ligas do tipo NiCr e Ni-Cr-Mo é mais complicada devido à formação de fases tais como a fase σ, µ e P, às quais são estabilizadas pela presença do molibdênio e também por adições de De acordo com Dupont (1996), a Figura 5 apresenta um constituinte secundário que exibe uma morfologia do tipo lamelar eutética, formado em regiões interdendríticas a partir da solidificação de uma solda de liga 625.…”

Section: Níquel E Suas Ligasunclassified

“…Figura 5 -Fotomicrografia de constituinte de segunda fase obtida por microscopia eletrônica de varredura. Dupont (1996) …”

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Resistência à fadiga de tubo API 5L X65 cladeado e soldado circunferencialmente com eletrodos de Inconel® 625

Santos¹

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São Carlos 2016As recentes descobertas de petróleo e gás na camada do Pré-sal representam um enorme potencial exploratório no Brasil, entretanto, os desafios tecnológicos para a exploração desses recursos minerais são imensos e, consequentemente, têm motivado o desenvolvimento de estudos voltados a métodos e materiais eficientes para suas produções. Os tubos condutores de petróleo e gás são denominados de elevadores catenários ou do inglês "risers", e são elementos que necessariamente são soldados e possuem fundamental importância nessa cadeia produtiva, pois transportam petróleo e gás natural do fundo do mar à plataforma, estando sujeitos a carregamentos dinâmicos (fadiga) durante sua operação. Adicionalmente, um dos problemas centrais à produção de óleo e gás das reservas do Pré-Sal está diretamente associado a meios altamente corrosivos, tais como H2S e CO2. Uma forma mais barata de proteção dos tubos é a aplicação de uma camada de um material metálico resistente à corrosão na parte interna desses tubos (clad). Assim, a união entre esses tubos para formação dos "risers" deve ser realizada pelo emprego de soldas circunferenciais de ligas igualmente resistentes à corrosão. Recent oil and gas discoveries in the Pre-Salt layer represent a huge exploration potential in Brazil, however, the technological challenges for the exploitation of these mineral resources are immense and therefore have motivated the development of studies looking for efficient methods and materials for their productions. The oil and gas pipellines, called risers, are elements that are necessarily welded and have fundamental importance in the production chain, since they transport oil and natural gas from the sea bed to the platforms and are subject to dynamic loads (fatigue) during operation. Additionally, one of the central problems in the production of oil and gas in the Pre-Salt reserves is directly associated with a highly corrosive media, such as H2S and CO2. A cheaper way to protect the pipelines from these medias is applying a protective layer of a corrosion resistant metal on the inner diameter of these pipes, creating a cladded pipe. Thus, a joining process of these pipes to form the risers must be carried out by the use of girth welds with a corrosion resistance material similar to the clad metal. As the welded structures are seen as potential location of "crack like" defects, to ensure the structural integrity of such component when subjected to repetitive loading conditions, it is necessary to know the fatigue crack growth rates for the girth weld. Therefore, in this work it was carried out fatigue crack propagation tests in the weld region of an API 5L X65 cladded pipe with Inconel ® 625, girth welded using Inconel ® 625 electrodes. From the welded region, Single Edge Notch Bending specimens, SEN(B), were removed with different thickness and width ratios (B/W= 0.5, 1, and 2). From the fatigue tests, the crack propagation rates (da/dN) as function of the variation of the stress intensity factor (ΔK), were determined for the weld ...

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Solidification of an alloy 625 weld overlay

Cited by 168 publications

References 10 publications

Microsegregation and Precipitates in Inconel 625 Arc Weld Overlay Coatings on Boiler Pipes / Mikrosegregacja I Wydzielenia W Powłokach Ze Stopu Inconel 625 Napawanych Łukowo Na Rury Kotłowe

Microsegregation and Precipitates in Inconel 625 Arc Weld Overlay Coatings on Boiler Pipes / Mikrosegregacja I Wydzielenia W Powłokach Ze Stopu Inconel 625 Napawanych Łukowo Na Rury Kotłowe

Analysis of Phase Transformations in Inconel 625 Alloy during Annealing

Resistência à fadiga de tubo API 5L X65 cladeado e soldado circunferencialmente com eletrodos de Inconel® 625

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