Residual stresses in forged IN718 turbine discs

Cihak, Ulrike; Staron, Peter; Marketz, W.; Leitner, Harald; Tockner, J.; Clemens, Helmut

doi:10.3139/146.018003

Cited by 14 publications

(12 citation statements)

References 14 publications

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“…All simulations with constant h showed a steady drop of the temperatures at the equivalent position ªMº in the FE model. As an example for a constant heat transfer the value h = 4000 W/(m 2 K) [7,8] was used to simulate the cooling behaviour within the plate and the disc as shown in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Residual Stresses in Compressor Discs for Aeroengines

et al. 2006

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Structural aeroengine components like forged high-pressure compressor discs are usually made of nickel-based superalloys due to their excellent high-temperature properties. [1] Especially Inconel 718 (IN718) is very widespread because of its excellent strength at elevated temperatures in combination with good fatigue and creep properties. [2] The specific performance of IN718 can mostly be attributed to the fine, semi-coherent c² precipitates, which act as a strengthening phase within the nickel matrix. c² is formed during a twostep aging sequence [3] which is performed after forging and before machining to final geometry. As dislocations represent potential nucleation sites for c² precipitates, rapid quenching to freeze dislocations increases the number of precipitates formed during the annealing cycle and, therefore, lead to a higher final strength. This optional heat treatment route which involves water quenching from the forging temperature, instead of solution annealing and subsequent air cooling, is referred to as ªdirect agingº. [4] However, water quenching leads to high residual stresses within the components. Although quenching is followed by the final aging treatment (with subsequent air cooling), residual stresses are not completely relieved. Therefore, heavy distortions of the forged component during machining to its final shape are still observed. These can lead to non-correctable deviations from COMMUNICATIONS

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Section: Resultsmentioning

confidence: 99%

Characterization of Residual Stresses in Compressor Discs for Aeroengines

et al. 2006

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“…Repeated measurements along three different radii 120° apart from each other showed a rotational symmetry of the stress state. Originally, the model was used with a constant heat transfer coefficient h = 4000 Wm -2 K -1 [2], which is based on data for water as reported in literature [20].…”

Section: Resultsmentioning

confidence: 99%

“…The results of our investigations on residual stresses (RS) in commercially produced forged compressor discs are reviewed [1][2][3][4][5][6]. The unique combination of high-temperature strength and high fatigue strength makes nickel-based superalloys suitable for turbine components [7,8].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Residual Stresses in 718 Turbine Discs by Neutron Diffraction and Finite Element Modelling

Staron

Cihak

Clemens

et al. 2011

AMR

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Abstract.The results of our investigations on residual stresses in commercially produced forged IN 718 compressor discs are reviewed. The residual stresses in the discs with a diameter of 320 mm and a thickness of up to 25 mm were studied using neutron diffraction to verify the predictions of a finite element simulation, which was used to model forging and cooling of the discs. In addition to the disc, a thin plate of the same material was also studied for testing the influence of specimen geometry on the model predictions. While the model results for the disc were not strongly influenced by the heat transfer coefficient, the stress distributions in the thin plate could only be predicted satisfactorily by using a temperature-dependent heat transfer coefficient that was derived from temperature measurements during quenching. Eventually, this led to an improvement of the FE simulation used for optimizing the production process.

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“…In order to verify the residual stress predictions of the FE simulation, residual stresses in a turbine disc that was taken out of the commercial production after forging and water quenching were studied by neutron diffraction. [6,7] Due to the relatively large dimensions of the part (∅ 320 mm, thickness up to 25 mm), neutron diffraction is the only experimental technique to study bulk residual stresses within the discs.…”

Section: Residual Stresses In Turbine Discsmentioning

confidence: 99%

“…As a consequence, the differences observed in Figure 5 most likely result from a positioning error. The simulation of the disc was initially performed using a constant heat transfer coefficient h = 4000 Wm -2 K -1 , [30] which is based on data for water as reported in literature. [31] Variations of this constant value within reasonable boundaries did not lead to a significant improvement of the model in terms of residual stress predictions for a disc.…”

Section: Reviewsmentioning

confidence: 99%

Diffraction‐Based Residual Stress Analysis Applied to Problems in the Aircraft Industry

Staron¹,

Cihak

Clemens

et al. 2007

Adv Eng Mater

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Cost reduction and weight saving are most important principles governing design and construction of aircrafts. Advanced alloys and thermo‐mechanical treatments as well as new and optimized production processes are being developed. For example, welding of fuselage components like stringers or clips made of Al alloys can have several advantages over riveting. Retention of optimum weld microstructure and properties as well as control of welding related residual stresses and distortion is essential. In the context of risk analysis and damage tolerance it will be of growing importance to study residual stress fields in weld configurations and their influence on fatigue crack propagation. In this paper, methods to evaluate residual stresses in turbine discs and laser welded Al joints are reviewed.

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Residual stresses in forged IN718 turbine discs

Cited by 14 publications

References 14 publications

Characterization of Residual Stresses in Compressor Discs for Aeroengines

Characterization of Residual Stresses in Compressor Discs for Aeroengines

Characterization of Residual Stresses in 718 Turbine Discs by Neutron Diffraction and Finite Element Modelling

Diffraction‐Based Residual Stress Analysis Applied to Problems in the Aircraft Industry

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