Microstructural simulation of nickel base alloy Incone* 718 in production of turbine discs

Brand, A.J.; Karhausen, Kai F.; Kopp, Reiner

doi:10.1179/026708396790122134

Cited by 17 publications

(20 citation statements)

References 4 publications

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“…[19,29,30,31] The reported values for WASPALOY, which is more similar to U720 from a structural point of view, are more scattered and lie in the ln s ϭ 39,666 Fig. 8-Estimation of flow stress as a function of strain rate using Eqs.…”

Section: Activation Energy For Deformationmentioning

confidence: 89%

“…Other workers have observed a similar behavior for different types of Ni-based superalloys in the lower range of the hot working temperature window (i.e., 950 °C to 1050 °C). [17,18,19] A detailed examination of the stress-strain curves of the samples deformed at 1100 °C and above for strain rates of 0.1 and 1 revealed the existence of a yield drop phenomenon (Figure 4(a)). The magnitude of the latter increased with the applied strain rate and temperature.…”

Section: Friction and Adiabatic Heatingmentioning

confidence: 98%

“…This type of configuration has been reported as being the main mechanism for dynamic recrystallization of materials in large grain structures. [19,32] The metallographic observations were corroborated to the method introduced by Poliak and Jonas to determine the critical strain for the initiation of dynamic recrystallization. [37] The results indicated that, for the experimental conditions used in this investigation, the critical strain for dynamic recrystallization is about 0.0975.…”

Section: Recrystallizationmentioning

confidence: 99%

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Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

Monajati

Taheri

Jahazi

et al. 2005

Metall Mater Trans A

146

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The hot deformation behavior of nickel-base superalloy UDIMET 720 in solution-treated conditions, simulating the forging process of the alloy, was studied using hot compression experiments. Specimens were deformed in the temperature range of 1000 °C to 1175 °C with strain rates of 10 Ϫ3 to 1 s Ϫ1 and total strain of 0.8. Below 1100 °C, all specimens showed flow localization as shear band through the diagonal direction, with more severity at higher strain rates. A uniform deformation was observed when testing between 1100 °C and 1150 °C with dynamic recrystallization as the major flow softening mechanism above 1125 °C. Deformation above ␥Ј solvus temperature was accompanied with grain boundary separation. The hot working window was determined to be in the interval 1100 °C to 1150 °C. Thermomechanical behavior of the material was modeled using the power-law, the Sellars-Tegart, and an empirical equation. The flow stress values showed a nonlinear dependence of strain rate sensitivity to strain rate. The analysis indicated that the empirical method provides a better constitutive equation for process modeling of this alloy. The apparent activation energy for deformation was calculated and its variations with strain rate and temperature are discussed.

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Section: Activation Energy For Deformationmentioning

confidence: 89%

Section: Friction and Adiabatic Heatingmentioning

confidence: 98%

Section: Recrystallizationmentioning

confidence: 99%

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Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

Monajati

Taheri

Jahazi

et al. 2005

Metall Mater Trans A

146

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“…In the last phase, as will be shown in Section III-E, the strain rate and strain are estimated to be 18.5 s À1 and 12.95, respectively. Thus, comparing the thermomechanical condition of the last phase with those of Brand et al study, [41] it is reasonable to presume that the temperature increase in the final stage is due to plastic work. Finally, as the high-temperature interface material was extruded to the sides, the temperature decreased.…”

Section: Temperature Measurements During Lfwmentioning

confidence: 96%

“…The influence of plastic work heat on the increase in the work piece temperature is reported by other researchers. For instance, Brand et al [41] reported a 323 K (50°C) temperature increase during hot compression of INCONEL 718 due to plastic work at deformation temperatures of 1423 K (1150°C) with a strain rate of 10 s À1 after a strain of 1. In the last phase, as will be shown in Section III-E, the strain rate and strain are estimated to be 18.5 s À1 and 12.95, respectively.…”

Section: Temperature Measurements During Lfwmentioning

confidence: 98%

Mechanical Property and Microstructure of Linear Friction Welded WASPALOY

Chamanfar

Jahazi

Gholipour

et al. 2010

Metall Mater Trans A

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The mechanical properties and microstructural evolution of WASPALOY joined by linear friction welding (LFW) were investigated in this study. In-situ temperature measurements using thermocouple probes indicated exposure of the weld area to a temperature of at least 1400 K (1126°C). Based on electron backscatter diffraction (EBSD) mapping of the weldments, up to 50 pct reduction in c grain size occurred within 0.9 mm of the weld interface as a result of dynamic recrystallization (DRX). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed that progressive dissolution of c¢ precipitates took place from the base metal to the weld interface, where almost no c¢ precipitates were observed. Within 3.3 mm of the weld interface, the c¢ dissolution significantly influenced the hardness profile measured across the extended thermomechanically affected zones (TMAZs). Investigation of strain distributions during tensile testing using the optical Aramis system revealed weak bonding at the edge of the weld due to oxidation. To extrude out oxide layers into the flash, increasing the axial shortening to higher than 1.2 mm is recommended.

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Effect of Process Modeling on Product Quality of Superalloy Forgings

Stockinger¹,

Riedler²,

Huber³

2010

Superalloy 718 and Derivatives

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Even so effects of forming, heating and cooling on microstructure and therefore mechanical properties are well understood for superalloys like alloy 718 the influence of complex multistep thermomechanical processes can not be described analytically. Thus the usage of simulation tools is a necessity in order to secure stable processes and resulting properties. With increasing computer power and the development of the finite element method it is today possible to simulate these processes with high accuracy in a sufficient time period. Typical simulation results like optimization of material input, a guaranteed die filling as well as prevention of folding or overheating will be part of the paper. In addition the benefits of recent developments on residual stress and distortion simulation as well as microstructure and nanostructure models and their influences on mechanical properties will be discussed. Finally some simulation examples including process variations and their effects on the quality of parts will be compared with results of microstructure evaluation and mechanical testing of forgings. Using these simulation approaches linked with recent developments on fatigue modeling, it is possible to obtain minimized weight and maximized lifetime in the final part and therefore optimize the total life cycle costs.

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Microstructural simulation of nickel base alloy Incone* 718 in production of turbine discs

Cited by 17 publications

References 4 publications

Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

Mechanical Property and Microstructure of Linear Friction Welded WASPALOY

Effect of Process Modeling on Product Quality of Superalloy Forgings

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