Crack Growth Behavior in ATI 718Plus&lt;sup&gt;®&lt;/sup&gt; Alloy

McDevitt, Erin; Oppenheimer, Scott M.; Kearsey, Rick; Tsang, J.

doi:10.4028/www.scientific.net/msf.706-709.2428

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…The effect of the η-phase on the mechanical properties of alloy 718Plus has received a good deal of attention, and it appears to depend strongly on the volume fraction, morphology and location of the precipitates [5,6,17,18]. A small amount of rod-shaped η particles, homogeneously distributed over most grain boundaries, is recommended to prevent notch sensitivity at high temperature and improve resistance to intergranular crack propagation [19].…”

Section: η Structure In a Rotating Disc Componentmentioning

confidence: 99%

Evolution of secondary phases in alloy ATI 718Plus^®during processing

Casanova

Martín-Piris

Hardy

et al. 2014

MATEC Web of Conferences

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Abstract. ATI 718Plus R is a polycrystalline Ni-base superalloy for aero-engine disc applications, which relies on the precipitation of η-phase (Ni 6 Nb[Al,Ti], D0 24 ) at grain boundaries for resistance to intergranular failure and grain size control. The nucleation and evolution of the η particles have been examined throughout the manufacturing process. During hot working below the η solvus, existing precipitates lose their orientation relationship with the matrix and become aligned with the forging flow. During heat treatment, a dual morphology develops by the uniform growth of those incoherent precipitates into coarse plates, together with the new nucleation of thin lamellae from selected grain boundaries. The balance between the two morphologies in the final component can be achieved by controlling precipitation and dissolution processes during forging.

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Section: η Structure In a Rotating Disc Componentmentioning

confidence: 99%

Evolution of secondary phases in alloy ATI 718Plus^®during processing

Casanova

Martín-Piris

Hardy

et al. 2014

MATEC Web of Conferences

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“…In the process of deformation, γ′ phase is difficult to deform, which leads to the formation of a weak zone interface between γ′ phase and matrix. In this case, microcracks are easily initiated at the γ/γ′ interface [17]. At the crack tip, the stress state is basically triaxial.…”

Section: Discussion and Analysismentioning

confidence: 99%

Correlation between Fracture Morphology and Microstructural Evolution during Long-Term Aging of EK61 Superalloy

Huang

Qin

et al. 2020

Scanning

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Microstructural evolutions of EK61 superalloy during long-term aging until 1000 h at 700°C and 750°C, respectively, are studied by combination of Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Impact fracture morphologies after aging for different time are observed by the SEM. The microstructure is found to be relatively stable during aging at 700°C, and the fracture morphologies are characterized by transgranular fracture. At 750°C, the coarsening of γ′ phase leads the reduction of the quantity of dimples, the chainization of carbides on grain boundaries leads to intergranular fracture, and the netting of η phases within grains leads to the formation of lamellar cleavage steps. It is obvious that the destabilization of precipitated phases affects fracture morphology significantly. The relationship between fracture morphology and the microstructure promotes the evaluation of service reliability of EK61 superalloy.

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The influence of crack and interface oxidation on dwell fatigue crack propagation behavior of the nickel-base superalloy ATI A718Plus

Kirchmayer,

Hausmann,

Gabel

et al. 2024

Metall Mater Trans A

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The crack propagation properties are an important and often limiting factor for the commercial application of superalloys in aerospace applications where the oxidation ahead of the crack tip plays an important role. Previous research on the Ni-base superalloy A718Plus revealed that the orientation and the volume fraction of the high temperature grain boundary phases δ and η have a major influence on the dwell fatigue crack propagation rate at 650 °C in ambient air but not in vacuum. In this work, the effect of internal oxidation at the η/δ–matrix interface and its effect on dwell fatigue crack propagation and mechanical properties are examined by advanced microscopic methods and micro-cantilever testing. During crack propagation, the crack tip is exposed to air where a Nb-rich oxide layer forms and embrittles the η/δ–matrix interface causing the cracks to deflect and propagate along the oxidized interfaces. Micro-cantilever tests on the oxidized interface show that these oxide layers also significantly reduce the local strength and fracture toughness of the material. This proves that interfacial oxide layers are the underlying reason for the reduction of the dwell fatigue crack growth resistance at 650 °C, particularly in microstructures whose η/δ–matrix interfaces are oriented parallel to the crack growth direction. Graphical Abstract

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Crack Growth Behavior in ATI 718Plus<sup>®</sup> Alloy

Cited by 6 publications

References 8 publications

Evolution of secondary phases in alloy ATI 718Plus^®during processing

Evolution of secondary phases in alloy ATI 718Plus^®during processing

Correlation between Fracture Morphology and Microstructural Evolution during Long-Term Aging of EK61 Superalloy

The influence of crack and interface oxidation on dwell fatigue crack propagation behavior of the nickel-base superalloy ATI A718Plus

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Crack Growth Behavior in ATI 718Plus<sup>®</sup> Alloy

Cited by 6 publications

References 8 publications

Evolution of secondary phases in alloy ATI 718Plus®during processing

Evolution of secondary phases in alloy ATI 718Plus®during processing

Correlation between Fracture Morphology and Microstructural Evolution during Long-Term Aging of EK61 Superalloy

The influence of crack and interface oxidation on dwell fatigue crack propagation behavior of the nickel-base superalloy ATI A718Plus

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Evolution of secondary phases in alloy ATI 718Plus^®during processing

Evolution of secondary phases in alloy ATI 718Plus^®during processing