Effects of Iron, Nickel, and Cobalt on Precipitation Hardening of Alloy 718

Groh, Jon; Radavich, J.F.

doi:10.7449/1991/superalloys_1991_351_361

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…Since the introduction of alloy 718 a significant number of alloys have been examined, including cast as well as wrought alloys, with the primary intent to maintain or improve properties and provide increased thermal stability while maintaining favorable processability. Some of the alloys [2][3][4][5][6][7][8][9][10] developed subsequently are shown along with 718, 718Plus® is a trademark of ATI Allvac Waspaloy, and René 41 in the development timeline of Figure 1a. A key requirement beyond strength, toughness, fatigue, creep, crack growth resistance, and processability which has also driven composition development is weldability.…”

Section: Introductionmentioning

confidence: 99%

“…A key requirement beyond strength, toughness, fatigue, creep, crack growth resistance, and processability which has also driven composition development is weldability. The relative weldability of various alloys has been graphically represented by Haafkens and Matthey 11 , and is modified to display other alloys including 718Plus in Figure 1b (a) (b) Figure 1: (a) Developments leading up to alloy 718 and subsequent efforts to improve capability over 718 [1][2][3][4][5][6][7][8][9][10] , and (b) relative weldability of various superalloys 11 plotted along with anticipated alloy 718Plus behavior based on chemistry.…”

Section: Introductionmentioning

confidence: 99%

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Metals Affordability Initiative: Application of Allvac Alloy 718Plus for Aircraft Engine Static Structural Components

Ott¹,

Groh²,

Sizek³

et al. 2005

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

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Mechanical property balance, malleability, and weldability of Alloy 718 have driven widespread utilization across the aerospace and non-aerospace industries for nearly 50 years. However, the metastability of the primary strengthening gamma double prime phase is typically unacceptable for applications above about 650°C. As a result, other more costly and difficult to process alloys, like Waspaloy, are used in such applications. The latter alloys, strengthened primarily by gamma prime, are also more sensitive to weld-related cracking than Alloy 718. As part of the Metals Affordability Initiative CORE Program, several alternate alloys were identified and evaluated for aircraft engine static structural component applications for use temperatures of at least 700°C. The application-integrated project team consisting of engine manufacturers, General Electric, Honeywell, and Pratt & Whitney; forgers Firth-Rixson and Ladish Co., Inc.; primary metal producers, Allvac and Carpenter Technology; and the Air Force Research Laboratory, selected the Allvac-developed 718Plus® alloy composition for scale-up and validation. Subscale and full-scale experiments confirmed that processability and weldability of this alloy were significantly improved relative to Waspaloy, approaching that of Alloy 718. Complex rolled rings varying in size from less than 25 to nearly 250 kg have been processed validating the advantages of this alloy. Assessment suggests capability similar to Waspaloy to 704°C has been achieved along with an acceptable balance of other properties. This paper will summarize the processing, weldability, and mechanical property evaluations successfully performed in this project, as well as progress toward industrial implementation of this alloy.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metals Affordability Initiative: Application of Allvac Alloy 718Plus for Aircraft Engine Static Structural Components

Ott¹,

Groh²,

Sizek³

et al. 2005

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

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“…Work by E. Raymond [4] indicates that delta solvus of 718 billet increases with nickel content in the 52-54% range. Other researchers [5] found no significant effect of nickel, cobalt, and iron levels on delta solvus temperature. Modeling simulations using the databases from Thermotech and CompuTherm predict conflicting trends for nickel.…”

Section: Introductionmentioning

confidence: 80%

Effect of Nickel Content on Delta Solvus Temperature and Mechanical Properties of Alloy 718

Frank¹,

Roberts²,

Zhang³

2010

Superalloy 718 and Derivatives

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Knowledge and control of the delta phase (Ni 3 Nb) solvus temperature is critical to optimize processing and heat treatment of alloy 718 for best mechanical properties. This is the case in aerospace applications where delta phase is used to produce fine grain structures during forging, and in oil-field applications where the delta phase is dissolved during solution treatment. Delta phase solvus is primarily controlled by niobium content. The effect of nickel content on delta phase solvus is not well understood as thermodynamic models and previous experiments have produced conflicting results. The purpose of this study was to confirm the effect of nickel content on delta solvus temperature using experimental heats and to document mechanical properties vs. nickel content. In addition, solvus results were compared with modeling predictions and an improved database was developed to more accurately predict delta phase solvus temperature in alloy 718.

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“…Numerous attempts have been made over the past several decades to improve temperature capability of Inconel 718, typically through chemistry modifications involving adjustment the content of Al, Ti and Nb and minor elements such as P and B. Cozar and Pineau firstly developed the compact morphology of γ″ and γ′ by adjustment Nb, Ti and Al content and their ratios, and found this special compact microstructure characterized with superior structure stability than that of the separated precipitation of γ″ and γ′ [3,4]. Subsequently, Tien, Guo, Radavich and Chang et al adjusted the Al/Ti ratio and (Al+Ti)/Nb ratio based on conventional Inconel 718 alloy, and the experimental results indicate that higher Al/Ti ratio and (Al+Ti)/Nb ratio can remarkably improve the structure stability of 718 alloy [5][6][7][8][9][10][11][12][13][14][15]. However, these experimental results mainly concentrate on the importance of γ″ and γ′ stability during long time aging and neglect other phases precipitation behavior.…”

Section: Introductionmentioning

confidence: 99%

Research on Inconel 718 Type Alloys with Improvement of Temperature Capability

Dong

Zhang

et al. 2010

Superalloy 718 and Derivatives

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Inconel 718 was developed by International Nickel Company in 1962, has become the most widely used superalloy in the world. The alloy's popularity is due to its excellent combination of mechanical properties, moderate price and good processability. However, its maximum use temperature is restricted to 650ºC because the main strengthening γ″ phase responsible for the alloy's outstanding properties rapidly overages. There has been a substantial amount of work by numerous investigations over the years to increase the temperature capability of Inconel 718. Xie and Dong et al. has systematically studied the effect of variation of alloying elements including Al, Ti, Nb, P, B, S and Mg etc. content on structural stability and mechanical properties by experiments and thermodynamic calculations.This attempt was made to improve the temperature capability of Inconel 718 via controlling the morphology of γ″ and γ′ phase and increase their solvus temperature by variation of Al, Ti and Nb content, and W addition for solid solution strengthening. The phases precipitation behaviors, long time microstructure stability and mechanical properties of modified 718 type alloys have been systematically studied. The results indicate that compact morphology of γ″ and γ′ has been observed in grains. In addition, a new stable globular phase with higher solvus temperature mainly precipitated at grain boundaries, different to the δ phase in conventional 718 alloy, has been observed in modified 718 type alloys (this phase is temporarily named δ′′ phase for description convenience). After 680ºC aging for 1,000h, the combination of δ′′ granular phase at grain boundaries and compact morphology precipitation of γ″ and γ′ phase in grains characterize with superior thermal stability. Preliminary mechanical properties test results show that the alloy with this kind of microstructure can provide better stress rupture properties and fatigue resistance than that of conventional Inconel 718. It appears to provide a new approach for improvement of temperature capability of Inconel 718 and the new designed 718 type alloy can be used at 680ºC or higher temperatures.

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Effects of Iron, Nickel, and Cobalt on Precipitation Hardening of Alloy 718

Cited by 7 publications

References 5 publications

Metals Affordability Initiative: Application of Allvac Alloy 718Plus for Aircraft Engine Static Structural Components

Metals Affordability Initiative: Application of Allvac Alloy 718Plus for Aircraft Engine Static Structural Components

Effect of Nickel Content on Delta Solvus Temperature and Mechanical Properties of Alloy 718

Research on Inconel 718 Type Alloys with Improvement of Temperature Capability

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