Microstructural modeling of metadynamic recrystallization in hot working of IN 718 superalloy

Medeiros, S.C.; Prasad, Y. V. R. K.; Frazier, William G.; Srinivasan, Raghavan

doi:10.1016/s0921-5093(00)01053-4

Cited by 219 publications

(95 citation statements)

References 11 publications

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“…When comparing the results from this investigation to those previously published, it is clear that there are distinct differences. Medeiros et al [5], amongst others, for example, have published equations relating the meta-dynamically recrystallised grains size to strain rate and temperature only. It is clear to see from these results that the time between the end of the deformation period and the time of analysis has a large influence on the observed grain size.…”

Section: Discussionmentioning

confidence: 99%

The Dynamic and Metadynamic Recrystallisation of IN 718

Guest¹,

Tin²

2005

Superalloys 718, 625, 706 and Various Derivatives (2005)

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The recrystallisation behaviour of IN 718 has been analysed using a Gleeble 1500 thermomechanical simulator. The use of a rapid water quenching system immediately after the compression test has resulted in the ability to separate dynamic behaviour from meta-dynamic. The rate of dynamic recrystallisation has been found to be proportional to temperature and strain, but inversely proportional to strain rate. The nucleation rate of recrystallised grains during deformation has been found to be directly linked to strain rate and temperature. The rate of meta-dynamic recrystallisation appears to be directly proportional to temperature and strain rate, but no new nucleation events were observed after the end of deformation MethodsMaterial was supplied for the experiments by Firth Rixson Forgings Ltd in the form of a forged and rolled billet of IN 718. Cylindrical samples of height 12 mm and diameter 8 mm were spark eroded from the billet and deformed using a Gleeble 1500 thermomechanical simulator.Initially, the effects of temperature and strain rate on dynamic recrystallisation were investigated. Samples were deformed at a temperature of either 980 • C or 1040 • C to predefined strains of 0·09, 0·18, 0·29, 0·41, 0·53, 0·67, and 0·82 at a set die velocity resulting in average strain rates of 0·01, 0·1, 0·45, and 1·1 s −1 followed by an immediate water quench. To investigate meta-dynamic recrystallisation, samples deformed to a strain of 0·82 were also held at the test temperature for times ranging from 1 second to 10 minutes before undergoing a water quench. Each experiment begins with a linear heat-up to test temperature over 2 minutes and then a hold for 1 minute. The tests were followed by a water quench designed to reduce the temperature of the sample as quickly as possible. Figure 1 shows the temperature profile of a typical test, showing the heat-up, hold, and quench. Thermal data is plotted for both the centre of the sample, and either end, measured using thermocouples welded to the sample. It can be seen that, although a large thermal gradient exists during the heating stage, after a 1 minute hold period, the sample is at a uniform temperature. Referring to Figure 1 (b), it can be seen that the water quench stage lowers the temperature of the specimen extremely rapidly. It takes only 1·1 seconds for the sample to reach 200 • C, and less than 0·2 seconds for the centre of the sample to fall below 800 • C (a temperature below which the rate of recrystallisation is almost zero).

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Section: Discussionmentioning

confidence: 99%

The Dynamic and Metadynamic Recrystallisation of IN 718

Guest¹,

Tin²

2005

Superalloys 718, 625, 706 and Various Derivatives (2005)

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“…The number of parameters is reduced when isothermal hot forging is performed. The literature gives many results for INCONEL 718 behaviour during a single pass hot deformation in the super-δ-solvus domain [1][2][3][4][5][6][7]. In the case of the super-δ-solvus domain, two papers only refer to multipass hot deformation [8][9]: the first study [8] was realized with an initial grain size of 250 µm (1200°C / 7 hours) much larger than the present grain size.…”

Section: Figure 1: Forging Domain Of Inconel 718mentioning

confidence: 99%

INCONEL718 Single and Multipass Modelling of Hot Forging

Jaeger¹,

Solas²,

Baudin³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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A better understanding of the competition between several mechanisms (dynamic recovery, dynamic recrystallization and plasticity hardening) is crucial for aircraft engine manufacturers. The aim of this paper is to improve the microstructure and therefore the mechanical properties of a nickel based superalloy used for rotating forged pieces. A nickel superalloy microstructure is the result of several successive hot forging processes: multipass processes, with intermediate dwell time and quenching. In this paper, an original three dimensional approach able to simulate these processes is proposed. The specific role of the different steps of the processes is analysed. In this approach, several forging thermo-mechanical parameters are taken into account: the working temperature, the strain rate, the final strain, the interpass time, etc. At high forging temperature, the studied INCONEL 718 presents an austenitic matrix γ (face centred cubic) assumed to be in a single phase.This approach proposes a sequential coupling of two models, one devoted to deformation and the other to recrystallization. Such a coupling enables the estimation of the effect of deformation and of different recrystallization types on mechanical behaviour and on micro-structural evolution. The approach is performed at the grain scale and takes into account the whole thermo-mechanical cycle with a focus on the dynamic behaviour.The first polycrystalline model is based on the plasticity mechanisms at the grains scale. The framework corresponds to finite transformations (large lattice rotations and small elastic strains). The model is implemented in ABAQUS and CAST3M finite element codes. The second model is based on the recrystallization theory and uses a 3D cellular automaton. It describes dynamic recrystallization phenomena such as nucleation-growth and static or postdynamic recrystallization. Such recrystallization mechanisms were observed during interpass time or during the successive heatings depending on the thermomechanical paths used in multipass forging. Dislocation densities are the internal variables common to the two models. The simulations are performed on a 3D Representative Elementary Volume (aggregate) obtained from Electron Back Scattering mapping. Numerical results are compared to experimental microstructures.

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“…The equation used to calculate the maximum possible growth rate is shown as Equation 5 (where R is the ideal gas constant, and T is the temperature in Kelvin). The value for the activation energy, Q, has been set to 240000 J mol −1 [9], and the factor c rx has been fitted to experimental data and set to 3·3×10 10 mm s −1 .…”

Section: Growing the Grains By Recrystallisationmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12]), they either fall into the category of being too simplistic and producing only an average grain size and approximate volume fraction recrystallised, or are far too complicated and too computationaly intensive to be used on a daily basis by process engineers. A model is required, therefore, that can be run within a commercially available finite element package, or in tandem with one, that will deliver detailed results, run in a reasonable time, and be simple to use.…”

Section: Introductionmentioning

confidence: 99%

Modelling Microstructural Transformations of Nickel Base Superalloy in 718 During Hot Deformation

Guest¹,

Tin

2005

Superalloys 718, 625, 706 and Various Derivatives (2005)

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A new Inconel 718 microstructural evolution model that works in tandem with finite element software is described, and is then used to predict the microstructure during the production of a typical two-stage forging route. The model works by grouping similar grains into grainsets and predicting the dislocation density within these grainsets during thermomechanical processing. The model is shown to accurately predict both the grain size and presence of δ precipitates during the processing route, and displays results both numerically and graphically.

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Microstructural modeling of metadynamic recrystallization in hot working of IN 718 superalloy

Cited by 219 publications

References 11 publications

The Dynamic and Metadynamic Recrystallisation of IN 718

The Dynamic and Metadynamic Recrystallisation of IN 718

INCONEL718 Single and Multipass Modelling of Hot Forging

Modelling Microstructural Transformations of Nickel Base Superalloy in 718 During Hot Deformation

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