The Metallurgy of Alloy 625

Floreen, S.; Fuchs, G.E.; Yang, Wen-xuan

doi:10.7449/1994/superalloys_1994_13_37

Cited by 186 publications

(187 citation statements)

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“…In the Alloy 625 used in this study, the chromium to molybdenum ratio was about 3. It has been reported earlier that at ageing temperatures above 850°C M,C type carbides form predominantly while at temperatures below 850 "C, M&, type carbides precipitate [6,8]. A limited amount of EDS analysis was carried out on this alloy in the present work and the results conformed to this observation.…”

Section: Nature Of Carbide Prechitatessupporting

confidence: 79%

“…High niobium contents are known to favour the formation of the MC phase in nickel base alloys [8]. The significant niobium content of Alloy 7 18 appeared to be responsible for promoting the precipitation of a niobium rich MC carbide.…”

Section: Nature Of Carbide Prechitatesmentioning

confidence: 98%

“…These carbide precipitates were found to have a cube to cube orientation relationship with the austenite matrix. Earlier investigations on this alloy have revealed that NbC and M,,C, type carbides form at grain boundaries when the ageing temperature is below 850°C while M,C type particles precipitate at higher temperatures [8].…”

Section: Alloy 718mentioning

confidence: 99%

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Carbide Precipitation in Nickel Base Superalloys 718 and 625 and Their Effect on Mechanical Properties

Sundararaman¹,

Mukhopadhyay²,

Banerjee³

1997

Superalloys 718, 625, 706 and Various Derivatives (1997)

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In addition to the precipitation of the strengthening intermetallic phases, namely, the metastable y" and y' phases, carbide phases also precipitate during age hardening heat treatments of Alloy 718 and Alloy 625. A detailed investigation has been carried out on the precipitation of primary and secondary carbide phases in these two alloys with reference to their identity, distribution and morphology. It has been found that the predominant carbide phase in Alloy 718 is a niobium rich MC phase, while in the case of Alloy 625, mainly M,,C, and, to some extent, M,C type carbides precipitate. Carbide precipitation during ageing has been seen to be confined almost exclusively to the austenite grain boundaries in both the alloys. NbC formation at the grain boundaries in Alloy 718 is associated with the appearance of distinct intermetallic precipitate ( y" and y' ) free zones near these boundaries whereas in Alloy 625, no well defined intermetallic precipitate free zones (PFZ) have been observed. The precipitation of different types of grain boundary carbides is discussed in terms of the differences in the chemistry of these alloys. The presence or absence of PFZ at grain boundaries is discussed in the light of solute depletion /vacancy depletion mechanisms.The influence of grain boundary carbide precipitation on the mechanical behaviour, especially the fracture mode, of these alloys has also been examined. It has been found that the progressive coverage of these boundaries with carbide particles results in a gradual transition in the fracture mode from transgranular to intergranular. Microcracks have often been found to nucleate at the matrix-carbide interface at the points of impingement of deformation bands.

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Section: Nature Of Carbide Prechitatessupporting

confidence: 79%

Section: Nature Of Carbide Prechitatesmentioning

confidence: 98%

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Carbide Precipitation in Nickel Base Superalloys 718 and 625 and Their Effect on Mechanical Properties

Sundararaman¹,

Mukhopadhyay²,

Banerjee³

1997

Superalloys 718, 625, 706 and Various Derivatives (1997)

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“…Under this circumstance it is the unique, and primary objective of this work 25 to analyse the effect of concomitant precipitate formation on the grain evolution of solution annealed Alloy 625.…”

Section: Introductionmentioning

confidence: 99%

Grain coarsening behaviour of solution annealed Alloy 625 between 600–800 °C

Moore

Taylor

Tracy

et al. 2017

Materials Science and Engineering: A

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As with all alloys, the grain structure of the nickel-base superalloy 625 has a significant impact on its mechanical properties. Predictability of the grain structure evolution in this material is particularly pertinent because it is prone to inter-metallic precipitate formation both during manufacture and long term or high temperature service. To this end, analysis has been performed on the grain structure of Alloy 625 aged isothermally at temperatures between 600-800 • C for times up to 3000 hours. Fits made according to the classical Arrhenius equation describing normal grain growth yield an average value for the activation energy of a somewhat inhomogeneous grain structure above 700 • C of 108.3±6.6 kJ mol −1 and 46.6±12.2 kJ mol −1 below 650 • C. Linear extrapolation between 650-700 • C produces a significantly higher value of 527.7 ± 23.1 kJ mol −1 . This result is ultimately a consequence of a high driving force, solute-impeded grain boundary migration process operating within the alloy.Comparison of the high and low temperature values with the activation energy for volume self-diffusion and grain boundary diffusion identifies the latter as the principle governing mechanism for grain growth in both instances. A decrease in the value of the time exponent (n) at higher temperatures despite a reduction in solute drag is attributable to the Zener pinning imposed by grain boundary M 6 C and M 23 C 6 particles identified from Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDXS) analysis.Vickers hardness results show the dominance of intermetallic intragranular precipitates in 1 the governance of the mechanical properties of the material with grain coarsening being accompanied by a significant increase in hardness. Furthermore, the lack of any correlation with grain growth behaviour indicates these phases have no significant effect on the grain evolution of the material.

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“…[19] Under thermal exposure, the solid solution decomposes and the various precipitate phases that are commonly found in the INCONEL 625 alloy are listed in Table II. [20] To determine the precipitated phases in the SPS samples, each phase listed in Table II was calculated using the program ''powder cell'' [21] to find a match with the peaks in the SPS samples in terms of position and intensity. Note that the C content after cryomilling is slightly higher than the typical chemistry range (0.01 to 0.04 wt pct C) in 625 alloy.…”

mentioning

confidence: 99%

Mechanical Behavior of Cryomilled Ni Superalloy by Spark Plasma Sintering

Zhang

Han

Huang

et al. 2009

Metall Mater Trans A

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The mechanical behavior of ultra-fine-grained (UFG) INCONEL 625 superalloy prepared via cryomilling and spark plasma sintering (SPS) was studied. The workhardening response of the ultra-fine-grained (600 to 700 nm) INCONEL 625 was compared to that of the material with a 1-lm grain size and the results showed normal work hardening for the latter material but not for the former. Moreover, the results suggest that a combination of high strength and good ductility can be simultaneously obtained in the UFG INCONEL 625 alloy.

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The Metallurgy of Alloy 625

Cited by 186 publications

References 1 publication

Carbide Precipitation in Nickel Base Superalloys 718 and 625 and Their Effect on Mechanical Properties

Carbide Precipitation in Nickel Base Superalloys 718 and 625 and Their Effect on Mechanical Properties

Grain coarsening behaviour of solution annealed Alloy 625 between 600–800 °C

Mechanical Behavior of Cryomilled Ni Superalloy by Spark Plasma Sintering

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