The influence of γ′-precipitation on the recrystallization of a nickel base superalloy

Dahlen, Milena; Winberg, L.

doi:10.1016/0001-6160(80)90039-5

Cited by 63 publications

(31 citation statements)

References 8 publications

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“…The void formation in the present study occurs during OP-TMF testing which imply compressive stresses at high temperature. Recrystallization at the grain boundaries and around particles has previously been observed and reported for other superalloys [23][24]. However, in these cases, the material was first plastically deformed, and then annealed at temperatures in the range of about 1050°-1200°C.…”

Section: Recrystallization and Oxidationmentioning

confidence: 55%

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Deformation and damage mechanisms in IN792 during thermomechanical fatigue

Kanesund

Moverare

Johansson

2011

Materials Science and Engineering: A

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The deformation and damage mechanisms arising during thermomechanical fatigue (TMF) of the polycrystalline superalloy IN792 have been investigated. The TMF cycles used in this study are in-phase (IP) and out-of-phase (OP). The minimum temperature used in all TMF-tests is 100°C while the maximum temperature is 500° or 750°C in the IP TMF-tests and 750°, 850° or 950°C in the OP TMF-tests. The majority of the cracks are transcrystalline, except for the IP TMF-test at 750°C, where some tendency to intercrystalline crack growth can be seen. In all tests, the cracks were initiated and propagated in locations where deformation structures such as deformation bands have formed in the material. In the temperature interval 750°-850°C, twins were formed in both IP and OP TMF-tests and this behaviour is observed to be further enhanced close to a crack. Twins are to a significantly lesser extent observed for tests with a lower (500°C) and a higher (950°C) maximum temperature. Recrystallization at grain boundaries, around particles and within the deformation structures have occurred in the OP TMF-tests with a maximum temperature of 850° and 950°C and this is more apparent for the higher temperature. Void formation is frequently observed in the recrystallized areas even for the case of compressive stresses at high temperature.

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Section: Recrystallization and Oxidationmentioning

confidence: 55%

“…In the later stage of recrystallization, second phase particles may act as pinning points for migrating boundaries and restrict the growth of the recrystallized grains [24]. The '-precipitates therefore play an important role in the recrystallization behaviour of Ni-base superalloys.…”

Section: Recrystallization and Oxidationmentioning

confidence: 99%

Deformation and damage mechanisms in IN792 during thermomechanical fatigue

Kanesund

Moverare

Johansson

2011

Materials Science and Engineering: A

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“…[9][10][11][12][13] During advancement of the grain boundary into the c/c¢ substrate, dissolution of c¢ precipitates occur at the moving boundary followed by discontinuous re-precipitation of c¢ once the boundary has advanced. [14] DP in turbine blades has significant implications on performance. Depletion of W and Re from the bulk matrix leading to precipitation and growth of TCP phases results in a loss of solid-solution hardening associated with these alloying elements and therefore a concomitant decrease in creep strength.…”

Section: Introductionmentioning

confidence: 99%

Discontinuous Precipitation in Ni-Base Superalloys During Solution Heat Treatment

Welton

D’Souza

Kelleher

et al. 2015

Metall Mater Trans A

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Discontinuous precipitation in single-crystal Ni-base superalloys during solution heat treatment has been studied. It is found that discontinuous precipitation occurs at temperatures approaching the solvus, where volume diffusion is dominant. Diffusion of Al ahead of the boundary leads to gamma prime precipitation and is accompanied by a loss in the driving force available for advancement of the grain boundary. The rate of gamma prime precipitation was tracked using in situ neutron diffraction during isothermal hold. Gamma prime precipitation is accompanied by super-saturation of Cr and W within the channels ahead of the interface. The driving force calculated for the initial stages of DP was [10-5 to 10-4] N/[lm 2 of the grain boundary]. The results provide an insight into discontinuous precipitation during solution heat treatment of Ni-base single-crystal alloys and are useful in optimizing the heat treatment process to avoid surface defect formation.

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“…Another study has been performed to explain dynamic recrystallization in the Ni-based superalloy Nimonic 80a by using a Gleeble 1500 system. The two studies show that recrystallization will take place at original grain boundaries in polycrystalline Ni-base superalloy [11,12]. The two studies have used higher temperature than the actual service temperature of a turbine blade.…”

Section: Recrystallizationmentioning

confidence: 99%

Influence of deformation and environmental degradation of Inconel 792

Kanesund¹

2017

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Industrial gas turbines are often used as a mechanical drive for pumps and compressors or in power generation as an electric power supply. The gas turbine has for many years been a popular engine due to its flexibility with respect to different types of fuel and due to a design, that enables a high power-to-weight ratio. A simplified description of a gas turbine is that the engine consists of a cold and hot section. The turbo compressor section belongs to cold section and the combustion chamber together with the turbine section belongs to the hot section. In the hot section of a gas turbine, the condition is extremely severe because of an aggressive environment characterized by high temperatures, increased temperature gradients, high pressure and centrifugal forces resulting in large stresses on individual components together with an oxidizing and corroding atmosphere. Materials used in the high temperature section (hot gas path) of a modern gas turbine are different types of superalloys, as single crystal, directionally solidified or polycrystalline alloys, depending on temperature and load conditions. In the first turbine stage, temperature is very high due to exposure to the combustion gas. To handle the problem with creep, single crystal superalloys are often used in this section. In the second row of turbine blades, the temperature of the gas is lower and polycrystalline superalloys are typically used. IN-792 is a cast polycrystalline superalloy with high strength, good resistance to hot corrosion and a cheaper option than single crystals. In the hot section of gas turbine, IN-792 is a suitable material for components such as turbine blades and vans where a complex load condition, high temperature and severe environment prevails. Due to startup and shutdown of the gas turbine engine during service, the components in the hot section are exposed to cyclic load and temperature. This will generate mechanical and thermal fatigue damage in gas turbine components. Steady state temperature gradient arises by the cooling system acting at cold spots during service to introduce tensile stress, which indirectly gives rise to creep damage in the component. This work includes tree studies of deformation and damage mechanisms of superalloy IN-792. The first study is made on test bars exposed to thermomechanical fatigue in laboratory environment, the second and the third study is made on turbine blades used during service. In the second study, the machines are placed off-shore and exposed to marine environment. In the third study the machine is landbased and exposed to an industrial environment. In the second study, the deformation and damage mechanisms are compared between the turbine blades used during service and the test bars exposed to thermomechanical fatigue testing in the first study.v

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The influence of γ′-precipitation on the recrystallization of a nickel base superalloy

Cited by 63 publications

References 8 publications

Deformation and damage mechanisms in IN792 during thermomechanical fatigue

Deformation and damage mechanisms in IN792 during thermomechanical fatigue

Discontinuous Precipitation in Ni-Base Superalloys During Solution Heat Treatment

Influence of deformation and environmental degradation of Inconel 792

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