Property Optimization in Superalloys Through the Use of Heat Treat Process Modelling

Wallis, R. A.; Bhowal, P. R.

doi:10.7449/1988/superalloys_1988_525_534

Cited by 8 publications

(5 citation statements)

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“…Wallis and Bhowal [11] have reported results from finite-element analyses used to model the temperature and stress evolution in superalloy turbine disc forgings subjected to forced air and oil quenching. Although their model output showed good correlation between the predicted and measured temperature evolution, the predicted stresses were not directly validated.…”

Section: Introductionmentioning

confidence: 99%

Residual stresses in a quenched superalloy turbine disc: Measurements and modeling

Rist

James

Tin

et al. 2006

Metall Mater Trans A

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A series of neutron diffraction measurements have been carried out to determine the elastic residual strains deep within a large, 40-cm-diameter, forged and water-quenched IN718 aeroengine compressor disc. Neutron path lengths of up to 6 cm were necessary to probe the thickest parts of the forging, and three-dimensional strain and stress components have been derived for the first time in such a large superalloy specimen. Measurements have been compared with the results from a coupled thermal-mechanical finite-element model of the quenching process, based upon appropriate temperature-dependent material properties, with some success. The general residual stress state in the disc is one of near-surface compression, balanced by tension within the disc interior. The steepest stress and strain gradients occur in the transition region from compression to tension, about 1 cm below the surface all around the disc. The largest stress component is in the disc tangential direction and reaches a magnitude of 400 to 500 MPa near the disc surface and at its core. This exceeds the effective yield stress because of the presence of significant hydrostatic stress.

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Section: Introductionmentioning

confidence: 99%

Residual stresses in a quenched superalloy turbine disc: Measurements and modeling

Rist

James

Tin

et al. 2006

Metall Mater Trans A

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“…Both the sizes and area fractions of different populations of precipitates are influential and therefore need to be quantified and modeled. These microstructural characteristics are strongly affected by the heat treatments a component undergoes (3)(4)(5). Previous work has often modeled precipitate size through heat treatments using cubic coarsening equations (5).…”

Section: Introductionmentioning

confidence: 99%

γ' Formation in a Nickel-Base Disk Superalloy

Gabb¹,

Backman²,

Wei³

et al. 2000

Superalloys 2000 (Ninth International Symposium)

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A streamlined,physics-based kinetic model was formulated, calibrated, and validated on a nickel-base superalloy. It was designed to be simplified and streamlined, to speed up calculations and facilitate linkage to finite element modeling thermal codes. The model describes and predicts the formation of y' precipitates during the heat treatment process. Standardized experimental methods were employed to calibrate and initially validate the microstructure model. The model was then validated on an oil-quenched generic disk. Predictions of primary cooling y' size and area fraction agreed well with experimental measurements over a large range of values and cooling rates.

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“…A lot of efforts have been made to simulate the cooling curve in a component, the residual thermal stress field to avoid quench cracking, and to study the relationship between cooling rate and mechanical properties. Figure 1.2, 1.3, 1.4 show the simulation results of the cooling profiles in a quenching component, residual stress and the strength prediction as a function of cooling rate, respectively [8,9]. It was seen in figure 1.4 that the strength increases with the increase of cooling rate.…”

Section: Processing-microstructure-mechanical Propertymentioning

confidence: 99%

“…Vf γ + Vf γ' = 1 [7][8][9][10] And the relationship between the γ-matrix energy G γ and the composition C γ is defined by the Gibbs energy function of the matrix,…”

Section: And Remember Thatmentioning

confidence: 99%

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Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys

Mao¹

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Precipitation-hardened nickel-based superalloys have been widely used as high temperature structural materials in gas turbine engine applications for more than 50 years. Powder metallurgy (P/M) technology was introduced as an innovative manufacturing process to overcome severe segregation and poor workability of alloys with high alloying contents. The excellent mechanical properties of P/M superalloys also depend upon the characteristic microstructures, including grain size and size distribution of γ′ precipitates. Heat treatment is the most critical processing step that has ultimate influences on the microstructure, and hence, on the mechanical properties of the materials. The main objective of this research was to study the γ′ precipitation kinetics in various cooling circumstances and also study the strength response to the cooling history in two model alloys, Rne88DT and U720LI. The research is summarized below: ACKNOWLEDGMENTS The author wishes to express her sincere thanks to her advisor, Dr. Keh-Minn Chang, for his continuously support, encouragement, and guidance he provided in the years passed. She would like to thank her colleagues Dr. Xingbo Liu and Dr. Zhengdong Long for their constructive suggestion on thermodynamic calculation and modeling approaches. Miss Li Yang, Mr. Matthew Burris, Mr. Robert Coulter and Dr. Longzou Ma provided their assistance at different stages during the research. Their contributions are also highly appreciated. The author would like to give Drs. David U. Furrer and Ganshu Sheng great appreciation for their generous support and constructive advice. She also appreciates the support from Diane Schwegler-Berry, NIOSH, Morgantown, WV, with the scanning electron microscope (SEM) operations. A special thanks is extended to Dr. Wanhong Yang for his solid assistance on the thermodynamic simulation and year-round encouragement. Finally, the author would like to acknowledge all the committee members for their time in reviewing the proposal and the dissertation, and their comments on various topics. v TABLE OF CONTENT CHAPTER 1. INTRODUCTION.

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Property Optimization in Superalloys Through the Use of Heat Treat Process Modelling

Cited by 8 publications

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Residual stresses in a quenched superalloy turbine disc: Measurements and modeling

Residual stresses in a quenched superalloy turbine disc: Measurements and modeling

γ' Formation in a Nickel-Base Disk Superalloy

Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys

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Property Optimization in Superalloys Through the Use of Heat Treat Process Modelling

Cited by 8 publications

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Residual stresses in a quenched superalloy turbine disc: Measurements and modeling

Residual stresses in a quenched superalloy turbine disc: Measurements and modeling

&#947;' Formation in a Nickel-Base Disk Superalloy

Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys

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γ' Formation in a Nickel-Base Disk Superalloy