Effects of Heat Treatment and Chemistry on the Long-Term Phase Stability of a High Strength Nickel-Based Superalloy

Keefe, P. W.; Mancuso, S.O.; Maurer, G. E.

doi:10.7449/1992/superalloys_1992_487_496

Cited by 39 publications

(31 citation statements)

References 2 publications

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“…It was possible to show that the somewhat minor change in composition of U720 to U720LI would cause a sharp drop in stability, consistent with the experimental results of Keefe et al [32]. However at that time it was not possible to calculate the TTT diagram.…”

Section: During Solidificationsupporting

confidence: 78%

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Modelling the Material Properties and Behaviour of Ni-Based Superalloys

Saunders¹,

Guo²,

Li³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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At the last two Superalloy meetings at Seven Springs, work on the development of thermodynamic modelling tools for application to multi-component Ni-based superalloys has been presented. Such modelling has become quite widespread, providing significant benefit. However, its applicability often falls short from directly providing the information that is actually required and, by itself, cannot be directly used to model properties being targeted by the end user, e.g. TTT/CCT diagrams, mechanical properties, thermophysical and physical properties. To overcome these limitations a new computer programme has been developed, called JMatPro, an acronym for Java-based Materials Properties software. The properties which can be calculated are wide ranging, including thermo-physical and physical properties (from room temperature to the liquid state), TTT/CCT diagrams, stress/strain diagrams, proof and tensile stress, hardness, coarsening of and and creep.

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Section: During Solidificationsupporting

confidence: 78%

“…However at that time it was not possible to calculate the TTT diagram. This has now been achieved and Figure 9 shows the calculated results with the experimental observations of Keefe et al [32]. The results match the different behaviour of the two alloys rather well.…”

Section: During Solidificationsupporting

confidence: 70%

Modelling the Material Properties and Behaviour of Ni-Based Superalloys

Saunders¹,

Guo²,

Li³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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“…The exponent ndBr takes 3 which is identical value in equation (1). Figure 6 shows the predicted average grain size and actual observed one in case of pancake forging.…”

Section: Modelinementioning

confidence: 57%

The Microstructure Prediction of Alloy720LI for Turbine Disk Applications

Matsui¹,

Takizawa²,

Kikuchi³

et al. 2000

Superalloys 2000 (Ninth International Symposium)

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In order to reduce the lead time of developmental stage and increase the reliability of the forging process of turbine disk, it is effective to predict the transformation of microstructure during the forging stage. In this paper, the microstructure prediction procedure for cast/wrought form alloy72OLI is introduced. To determine the parameters quantitatively, two kinds of tests were carried out. One was isothermal heating test, the other was isothermal compression test. The relational expressions between microstructure and various parameters e.g. time, temperature and strain rate were formulated for both static grain growth model and dynamic recrystallization model. Static grain growth model and dynamic recrystallization model represents preheating process prior to forging and forging process itself respectively. The models were coupled to finite element analyzing system. Furthermore pancake forging and generic shaped disk forging were carried out to verify the effectiveness of proposed prediction system. It was confirmed that the proposed prediction system has good accuracy to apply to the actual disk forging process.High performance alloys are used for turbine disks and the requirement for its properties and reliabilities are increasing for advanced aircraft engines. Alloy720LI is one of the most effective alloy for turbine disk applications because of its high creep strength and low cycle fatigue (LCF) property at elevated temperature. In fact, several engine adopt alloy720LI as turbine disk material. Alloy720LI was developed as for both cast/wrought alloy and powder metallurgy (P/M) alloy. Many investigations were performed in both regionsId. Each has advantages and disadvantages. Generally cast/wrought form is more desirable compared to P/M form from the viewpoint of cost. Advanced aircraft engine requires not only improvement of properties but also reduction of cost. Therefore cast/wrought form is worthy of being investigated further. As for properly, cast/wrought process can give excellent creep and LCF property, much the same to P/M process. But it is difficult to give such high properties in actual parts. Alloy720LI include higher alloying elements than conventional alloys e.g. alloy718 and has greater temperature and strain rate dependence on various behaviors. Especially deformation resistance and microstructure behavior are important to produce the disk. The former restricts disk size and shape, the latter is related to final mechanical properties. Various parameters e.g. temperature, strain rate, total strain etc. have to be controlled carefully to obtain desirable mechanical properties through out any portion of disk. In case of cast/wrought process, the control of such Superalloys 2003 Edited byT

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“…However, experience has shown that a level of 18 wt.% in alloy 720 causes excessive precipitation of σ and µ phases after relatively short exposure times above 700ºC 2,11 . Since these phases are known to degrade the creep properties of nickel disc alloys 12,13 , a balance between improved fatigue crack growth resistance and reduced TCP phase formation was struck at around 15 wt.% chromium.…”

Section: Alloy Compositionmentioning

confidence: 99%

Developing Damage Tolerance and Creep Resistance in a High Strength Nickel Alloy for Disc Applications

Hardy¹,

Zirbel²,

Shen³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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The development of an affordable nickel disc alloy that shows the required combination of strength, damage tolerance and creep resistance continues to challenge materials engineers. RollsRoyce has developed the alloy known as RR1000, which when processed to produce a fine grain microstructure, shows at least a 25ºC increase in temperature capability over the current disc alloy, 720Li, and has an equivalent crack growth resistance to coarse grain Waspaloy. This paper discusses the steps that were taken to attain these mechanical properties, and also examines the potential to increase temperature capability by a further 30ºC through the development of a coarse microstructure in selected areas of disc forgings.

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Effects of Heat Treatment and Chemistry on the Long-Term Phase Stability of a High Strength Nickel-Based Superalloy

Abstract: Phase stability of UDIMET@ alloy 720 (U720), a high strength, @ Registered Trademark of Special Metals Corporation

Cited by 39 publications

References 2 publications

Modelling the Material Properties and Behaviour of Ni-Based Superalloys

Modelling the Material Properties and Behaviour of Ni-Based Superalloys

The Microstructure Prediction of Alloy720LI for Turbine Disk Applications

Developing Damage Tolerance and Creep Resistance in a High Strength Nickel Alloy for Disc Applications

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