Grain Boundary Engineering the Mechanical Properties of Allvac 718Plus™ Superalloy

On the precipitation of delta phase in ALLVAC®718Plus

“…Some found the precipitates beneficial to fatigue and creep properties [21,22] whilst others suggest that the precipitation is detrimental [23]. Such variability suggests that mechanical properties are strongly related to the volume fraction and morphology of the precipitates within the structure and hence the thermo-mechanical history [24][25][26]. In this paper, we examine in detail the structure of these multiphase precipitates and from the structures are able to draw conclusions about their growth.…”

Environmental and Dwell Effects on the Damage Tolerance Properties of ATI 718Plus® Alloy

“…What is also significant about their findings is that the δ-containing 718Plus heat treatment condition displayed a bimodal γ′ distribution of ~30nm and 130nm. The fracture modes associated with these bimodal γ′, δ-containing microstructures also exhibited a larger fraction of transgranular deformation when compared to the unimodal, δ-free structures investigated [15]. Therefore, the observed improved dwell-fatigue crack propagation resistance of HT2 in the present study may be strongly related to the coarsening of the γ′ hardening phase during thermal exposure, with potential further improvement in dwell-FCGR properties via [15], is c present study fo discussed earlie deformation duri EDX analysis wa along the dwell f EDX map in Fig phase parallel Figure 7 gh not as prev mena, two type gly observed al es appeared to b number contras spot analysis, sh particles were Nb articles was that ed and located b -coloured carbid predominantly ns or just ahead observations are bserved in Nb-co es near grain bo tibility during fa onducted in lab a mode that is pred 7.…”

“…In fact they showed identical dwell-FCGR behaviour [5,7]. Recent studies performed by Gabb et al, have examined the effect of modifying the microstructure of 718Plus via grain boundary engineering (GBE) practices while maintaining grain boundary size features [15]. In their work, they determined that the incorporation of a δ phase heat treatment, thereby promoting δ along the grain boundaries, imparted superior dwell-FCGR properties when compared to the δ-free 718Plus microstructure [15].…”

“…Recent studies performed by Gabb et al, have examined the effect of modifying the microstructure of 718Plus via grain boundary engineering (GBE) practices while maintaining grain boundary size features [15]. In their work, they determined that the incorporation of a δ phase heat treatment, thereby promoting δ along the grain boundaries, imparted superior dwell-FCGR properties when compared to the δ-free 718Plus microstructure [15]. What is also significant about their findings is that the δ-containing 718Plus heat treatment condition displayed a bimodal γ′ distribution of ~30nm and 130nm.…”

In Situ Characterization of Inconel 718 Post-Dynamic Recrystallization within a Scanning Electron Microscope

“…Special attention will thus be given to the impact of the initial dynamically recrystallized fraction. In addition, because there is an increasing interest given to the grain boundary networks in nickel-based superalloys [23][24][25][26][27][28][29][30][31] (in the perspective of grain boundary engineering [32]), the evolution of annealing twins along with post-dynamic recrystallization will also be described.…”