Repair Weldability Studies of Alloy 718 Using Versatile Varestraint Test

Chou, Chia-Jui; Chao, Chia-Wei

doi:10.7449/1988/superalloys_1988_785_793

Cited by 2 publications

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“…Furthermore, variation in heat treatment cycles may result in grain boundary segregation and/or increase the fraction of some secondary phases (e.g. δ-phase in IN718) increasing the propensity for grain boundary liquation during nil strength experiments [14,31,33]. On the basis of the obtained results, it could be said that the NST value does not seem to be very sensitive to the heating rate and that variations are more sensitive to chemical composition and thermal cycle applied to the alloy.…”

Section: Nil Strength Temperaturementioning

confidence: 99%

Hot ductility behavior of AD730™ nickel-base superalloy

Tabaie

Shahriari

Plouze

et al. 2019

Materials Science and Engineering: A

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Hot ductility of the newly developed AD730 TM nickel-base superalloy was investigated in the temperature interval 1050-1240°C. The nil strength and nil ductility temperatures were determined by hot tensile testing using the Gleeble TM 3800 weld thermal simulation method. The influence of heating rate, representing the weld thermal cycle, on hot ductility behavior of the alloy was also investigated. The microstructure and the fracture mode of samples were examined by optical and scanning electron microscopy. The influence of heating rate on the extent of grain boundary liquation and void formation was determined and it is shown that the significant ductility loss near the NDT point could be related to the reduction of surface tension at the grain boundary-matrix interface. In addition, the contribution of hard precipitates, such as grain boundary MC carbides, voids, and cavities as other damage mechanisms responsible for ductility loss at high temperature, are discussed.

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Section: Nil Strength Temperaturementioning

confidence: 99%

Hot ductility behavior of AD730™ nickel-base superalloy

Tabaie

Shahriari

Plouze

et al. 2019

Materials Science and Engineering: A

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Tailoring alloy 718 laser directed energy deposition process strategies for repair applications

Jamieson

Brennan

Spurgeon

et al. 2022

Journal of Laser Applications

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Laser-based directed energy deposition (LDED) for repair and sustainment has become a viable alternative to replace or complement traditional repair applications. Many a time, thin-walled structures cannot be repaired because of the heat intensive repair operations, which lead to excessive distortion or degradation of the parent material. To overcome repair challenges related to thin-walled structures, a low-energy process strategy with powder feedstock has been developed to reduce the heat-affected zone, reduce distortion, and produce a microstructure yielding higher microhardness values. On the other side of the repair spectrum, much larger surfaces may also need attention. In this case, a high-deposition rate process strategy may be more suitable to reduce lead-time and cost. To accommodate larger repairs, a high-deposition rate process strategy using wire feedstock has been developed. The high-deposition rate strategy is shown to be more cost-effective provided the target application and part geometry can accommodate the high-energy process. Validating these LDED repair strategies has been accomplished by analyzing the resulting distortion, presence of flaws or defects, microhardness, microstructure, and tensile properties. The process control offered by LDED through the ability to tailor the process-structure-property relationships of a material system depending on component geometry and application has put a new tool in place addressing many concerns related to traditional arc-based repair processes.

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Repair Weldability Studies of Alloy 718 Using Versatile Varestraint Test

Abstract: The effect of multiple

Cited by 2 publications

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Hot ductility behavior of AD730™ nickel-base superalloy

Hot ductility behavior of AD730™ nickel-base superalloy

Tailoring alloy 718 laser directed energy deposition process strategies for repair applications

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