Creep behavior of INCOLOY alloy 617 (original) (raw)

Microstructural analysis of creep exposed IN617 alloy

2010

Nickel base alloys such as IN617 are one of the preferred choices for steam turbine components used by fossil fuelled power generation plants. IN617 is a solid-solutionstrengthened nickel-based superalloy containing ~23% Cr, 12% Co, and 9% Mo with low content of precipitation-strengthening elements Al, Ti and Nb. In the 'as-received' (solution-annealed condition), the microstructure consists of primary carbides (M 23 C 6 ) and occasional TiN particles dispersed in a single-phase austenitic matrix. Owing to high temperature exposure and the creep deformation processes that occur in-service, evolution of the microstructure occurs. This results in secondary precipitation and precipitate coarsening, both on grain boundaries and intragranularly in areas of high dislocation density. The influence of creep deformation on the solution-treated IN617 alloy at an operating condition of 650˚C/574 Hrs, with emphasis on the morphology and distribution of carbide/nitride precipitation is discussed. The applied stress was at an intermediate level.

Precipitate Redistribution during Creep of Alloy 617

Metallurgical and Materials Transactions A, 2009

Nickel-based superalloys are being considered for applications within advanced nuclear power generation systems due to their high temperature strength and corrosion resistance. Alloy 617, a candidate for use in heat exchangers, derives its strength from both solid solution strengthening and the precipitation of carbide particles. However, during creep, carbides that are supposed to retard grain boundary motion are found to dissolve and re-precipitate on boundaries in tension. To quantify the redistribution, we have used electron backscatter diffraction and energy dispersive spectroscopy to analyze the microstructure of 617 after creep testing at 900 and 1000°C. The data were analyzed with respect to location of the carbides (e.g., intergranular vs. intragranular), grain boundary character, and precipitate type (i.e., Cr-rich or Mo-rich). We find that grain boundary character is the most important factor in carbide distribution; some evidence of preferential distribution to boundaries in tension is also observed at higher applied stresses. Finally, the results suggest that the observed redistribution is due to the migration of carbides to the boundaries and not the migration of boundaries to the precipitates.

Microstructural Changes in IN617 Superalloy during Creep at High Temperatures

Procedia Engineering, 2014

In an Ultra super critical power plant, it is considered to be necessary to use Ni-base super alloys with higher strength in addition to conventional heat-resistant steel. Out of various materials in the pipe line, one important alloy i.e. IN 617 super alloy is selected for the Ultra Supercritical power plant applications for operation. Creep is one of the major properties to be assessed for the material to be used in USC power plants. In this paper, creep behaviour of IN 617 super alloy is studied at various stress and temperatures and microstructures are correlated with high temperature properties. Microstructures of crept samples tested at two temperatures of 650 o C and 700 o C at different stress level were analysed and compared using optical and scanning electron microscopy techniques.

Creep behavior of ingot and powder metallurgy 6061Al

Journal of Alloys and Compounds, 2007

The creep behavior of 6061Al alloy obtained by ingot metallurgy and powder metallurgy, IM and PM, respectively, has been investigated in the context of published studies on this alloy. The behavior of the IM alloy in a given range of temperatures where the b, Mg2Si, precipitates are formed, is dominated by dislocation climb-controlled creep and aluminum self-diffusion as rate controlling process. A dependence of the b inter-particle distance, l, with the applied stress, s, of the form is found when the creep data are analyzed in the context of the sub-structure invariant model. The superior creep resistance of the PM material can be explained if a threshold stress, s0, is brought into the creep equation. This term is the difference between the applied stresses needed to reach a given strain rate in the PM and the IM alloys, and correlates well with a particle-dislocation interaction mechanism according to the Artz-Wilkinson model.

The Microstructure Changes in IN713LC during the Creep Exposure

Advanced Materials Research, 2011

Nickel-based creep resisting alloys (strengthened by γ´) are the basic materials for high-temperature constructional parts in aircraft engines and energy units. These parts are exposed to combined effects of mechanical stresses, high temperature and dioxide-corrosion conditions. The microstructure changes of cast polycrystalline Ni-based superalloy IN713LC after creep exposure were studied. Three specimens with three different diameters were used for creep tests. The degradation stage (damage parameter π) was determined for all parts of specimens. Individual parts of specimens were metallographic observed and analyzed by image analysis after rupture. The results were compared with model of stress distribution in the specimen with potential damage in the centre of the specimen.

Assessment of creep damage models in the prediction of high-temperature creep behaviour of Alloy 617

International Journal of Pressure Vessels and Piping, 2019

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Microstructural characterization of Inconel 713 C superalloy after creep testing

2018

The main aim of this investigation was to determine the microstructural degradation of Inconel 713C superalloy during creep at high homologous temperature. The alloy in as cast condition was characterized by large microstructural heterogeneity. Inside equiaxed grains dendrite cores consisted of γ' precipitates surrounded by channels of matrix, whereas enrichment of interdendritic spaces in carbide formers, Zr and B resulted in the formation of additional constituents, namely M3B2, Ni7Zr2 and eutectic island γ/γ'. Directional coarsening of γ′ precipitates (rafting) under applied stress and decomposition of primary MCtype carbides accompanied by the formation of secondary carbides enriched in Cr and γ' phase was observed.

Analysis of Creep Tests of the in 792-5 a Alloy

2009

IN 792-5A, a variant within the IN 792 alloy series, is a high-temperature cast nickel alloy strengthened by the presence of precipitates of the γ’ phase and carbides. This alloy is currently used, for instance, as the material of cast blades for jet engines. The companies UJP PRAHA a.s and PBS Velká Bíteš a.s. have joined their research capacities in a project aimed to identify the properties of the alloy with focus on its heat treatment. Within the project, creep tests of the IN792-5A alloy as cast and following three-step heat treatment were performed in cooperation with the Institute of Physics of Materials, Academy of Sciences of the Czech Republic. Such heat treatment was found to extend appreciably the alloy’s creep life. In the as-cast state the alloy fails to meet the requirements for its lifetime. The present contribution discusses the causes of the differences in the creep behaviour of the IN792-5A alloy between the two structure states. The structure of the alloy and the...