Journal ArticleDOI
Effect of boron on fatigue crack growth behavior in superalloy IN 718 at RT and 650 °C
TLDR
In this paper, the effect of boron on the fatigue crack growth rate in Inconel 718 (IN 718) was studied at room temperature (RT) and 650°C.Abstract:
The effect of boron on the fatigue crack growth rate (FCGR) in Inconel 718 (IN 718) was studied at room temperature (RT) and 650 °C The results showed that the addition of B improved the fatigue crack propagation resistance of IN 718 The higher the B concentration, higher was the fatigue threshold at 650 °C While the FCGRs increased as the test temperature increased from RT to 650 °C in the Paris regime, a rapid drop in the FCGRs in the near-threshold regime and a higher fatigue threshold at 650° were observed due to the oxide-induced crack closure The fracture surfaces were observed to exhibit transgranular cracking with fatigue striations in specimens tested at RT, and a mixture of transgranular and intergranular cracking at 650 °C The fracture mode changed from intergranular cracking to transgranular cracking and plastic deformation marks increased with increasing B concentration at 650 °C The micromechanism of improvement in the fatigue crack growth resistance due to B addition was further studied via observations of crack growth path, fractography and TEM examination of the plastic zone ahead of the crack tip The plastic deformation mode within the crack tip plastic zone was planar slip, along with twinning, on {1 1 1} planes A crystallographic cracking model was, thus, proposed on the basis of restricted slip or twinning The improvement in the fatigue crack growth resistance in IN 718 due to B addition was mainly attributed to the increase in the grain boundary cohesion via minimizing the deteriorative effect of oxygen and the increase in the resistance to the dislocation movement at the crack tipread more
Citations
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Journal ArticleDOI
High temperature fatigue of nickel-base superalloys - A review with special emphasis on deformation modes and oxidation
TL;DR: In this article, a review of Ni-base superalloys in terms of fundamental deformation mechanisms, environmental effects, and interactions between environment and deformation mode is presented, where the basic principles that are developed are used to show how both intrinsic and extrinsic variables can be manipulated to control fatigue behaviour and as a guide for formulation of engineering life prediction models.
Journal ArticleDOI
Hot isostatic pressing of IN718 components manufactured by selective laser melting
TL;DR: In this article, the influence of the HIP process parameters on the density and microstructure of IN718 SLM components is investigated by means of micro X-ray computed tomography and scanning electron microscopy.
Journal ArticleDOI
The influence of Laves phases on the high-cycle fatigue behavior of laser additive manufactured Inconel 718
TL;DR: In this paper, a comparative study of high-cycle fatigue tests (T=650°C, f=110 Hz, R=0.1, Kt=1) were carried out with wrought Inconel 718 and LAMed Inconels 718, and the results showed that the influences of the Laves phases on highcycle fatigue properties are based on the applied stress amplitudes.
Journal ArticleDOI
On the effect of boron on grain boundary character in a new polycrystalline superalloy
Paraskevas Kontis,H.A. Mohd Yusof,S. Pedrazzini,Mohsen Danaie,Katie L. Moore,Paul A. J. Bagot,Michael P. Moody,Chris R. M. Grovenor,Roger C. Reed +8 more
TL;DR: The role of boron in conferring the grain boundary character in a new polycrystalline superalloy suitable for power generation applications is considered in this article, using a suite of high resolution characterisation techniques including atom probe tomography (APT), high resolution secondary ion mass spectroscopy (SIMS), and transmission electron microscopy (TEM).
Journal ArticleDOI
Crack growth micro-mechanisms in the IN718 alloy under the combined influence of fatigue, creep and oxidation
TL;DR: In this article, a review of the different phenomena responsible for crack growth in the IN718 nickel-base superalloy under the combination of fatigue, creep and oxidation is presented.
References
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Journal ArticleDOI
Low Cycle Fatigue Behavior of Inconel 718 at 298 K and 823 K
D. Fournier,André Pineau +1 more
TL;DR: In this article, the cyclic stress-strain response and the low cycle fatigue life of conventionally heat treated Inconel 718 were studied using optical and electron microscopy.
Journal ArticleDOI
Coherency strengthening in Ni base alloys hardened by DO 22 γ' precipitates
TL;DR: The strengthening phase in nickel-base Alloy 718 is a metastable DO22 precipitate termed γ′ which is based upon Ni3Nb as discussed by the authors, and it can be controlled by the application of stress during aging.
Journal ArticleDOI
Deformation behaviour of γ″ strengthened inconel 718
TL;DR: In this paper, the deformation mechanisms of a strengthened nickel base alloy (Inconel 718) have been studied and a new type of precipitate shearing mechanism has been shown.
Journal ArticleDOI
Fatigue behaviour of two nickel-base alloys I: Experimental results on low cycle fatigue, fatigue crack propagation and substructures
M. Clavel,André Pineau +1 more
TL;DR: In this paper, the low cycle fatigue and fatigue crack propagation of Inconel 718 alloy and Waspaloy were investigated at 25, 550 and 650 °C and the qualitative observations indicate that there exists a close correspondence between the near-threshold regime and stage I crack initiation in low-cycle fatigue.
Journal ArticleDOI
Shearing of γ″ precipitates and formation of planar slip bands in Inconel 718 during cyclic deformation
TL;DR: Inconel 718 at RT and 650°C caused the formation of planar deformation bands and shearing of coherent and ordered γ″ and γ′ precipitates by paired dislocations.