“…The specific level of strain where there is limited nucleation dictates the critical strain range where AGG occurs and depends on the alloy composition [15]. For example, in the FGH96 superalloy, AGG has been reported to occur within a strain region of 0.02-0.1 [22], whereas in René 65 it has been observed at a strain of 0.15 [9]. Below the critical window, the strain is too low to induce recrystallisation via SIBM and only recovery and NGG occur.…”
Section: Abnormal Grain Growthmentioning
confidence: 99%
“…Abnormal grain growth (AGG) refers to selective grain growth within a critical window of strain or strain rate resulting in a small fraction of abnormally large grains (ALGs) among a fine microstructure, as shown in Figure 10 [12]. These abnormally large grains have been reported to be up 10 times larger than their smaller neighbours and possess a high density of annealing twin boundaries [9]. Figure 10 Inverse pole figure (IPF) map of an abnormally large grain in FGH96 superalloy captured using electron backscatter diffraction techniques [22].…”
Section: Microstructure Evolution During Post-deformation Heat Treatm...mentioning
confidence: 99%
“…For example, Flageolet et al [8] studied abnormal grain growth in Inconel 718 and deduced that a bimodal grain structure, consisting of a few anomalously large grains within an otherwise fine microstructure, imparted deleterious properties on turbine disc components such as reduced cycle fatigue resistance [8]. Despite the effect of these inhomogeneous grain structures being well known, crucially, their development during thermomechanical processing (TMP) and subsequent heat treatments is still much debated in the literature [9].…”
The effects of manufacturing conditions on the microstructure evolution of Ni-based superalloys are poorly understood, and the interchangeable terminology to describe some microstructure phenomena is inconsistent. This critical review aimed to address these issues through the discussion of seven microstructure phenomena that occur during thermomechanical processing of safety-critical components used in jet engines. Each phenomenon is outlined with reference to grain nucleation and growth mechanisms, as well as processing conditions under which they are observed. The processing conditions where each phenomenon dominates are visualised through a series of contour plots. Through this graphical representation, gaps of understanding in microstructure evolution were identified and accompanied by recommendations for areas of further study.
“…The specific level of strain where there is limited nucleation dictates the critical strain range where AGG occurs and depends on the alloy composition [15]. For example, in the FGH96 superalloy, AGG has been reported to occur within a strain region of 0.02-0.1 [22], whereas in René 65 it has been observed at a strain of 0.15 [9]. Below the critical window, the strain is too low to induce recrystallisation via SIBM and only recovery and NGG occur.…”
Section: Abnormal Grain Growthmentioning
confidence: 99%
“…Abnormal grain growth (AGG) refers to selective grain growth within a critical window of strain or strain rate resulting in a small fraction of abnormally large grains (ALGs) among a fine microstructure, as shown in Figure 10 [12]. These abnormally large grains have been reported to be up 10 times larger than their smaller neighbours and possess a high density of annealing twin boundaries [9]. Figure 10 Inverse pole figure (IPF) map of an abnormally large grain in FGH96 superalloy captured using electron backscatter diffraction techniques [22].…”
Section: Microstructure Evolution During Post-deformation Heat Treatm...mentioning
confidence: 99%
“…For example, Flageolet et al [8] studied abnormal grain growth in Inconel 718 and deduced that a bimodal grain structure, consisting of a few anomalously large grains within an otherwise fine microstructure, imparted deleterious properties on turbine disc components such as reduced cycle fatigue resistance [8]. Despite the effect of these inhomogeneous grain structures being well known, crucially, their development during thermomechanical processing (TMP) and subsequent heat treatments is still much debated in the literature [9].…”
The effects of manufacturing conditions on the microstructure evolution of Ni-based superalloys are poorly understood, and the interchangeable terminology to describe some microstructure phenomena is inconsistent. This critical review aimed to address these issues through the discussion of seven microstructure phenomena that occur during thermomechanical processing of safety-critical components used in jet engines. Each phenomenon is outlined with reference to grain nucleation and growth mechanisms, as well as processing conditions under which they are observed. The processing conditions where each phenomenon dominates are visualised through a series of contour plots. Through this graphical representation, gaps of understanding in microstructure evolution were identified and accompanied by recommendations for areas of further study.
“…For example, in a highstrain-rate shock-loaded tantalum sample (gas-gun experiment), large misorientation gradients are observed within grains near the spallation front where significant voiding has occurred. 85 Furthermore, micron-scale annealing twins are resolved in the nickel-base superalloys Inconel 718 86 and Rene 65 87 by direct EBSD mapping of laser-ablated surfaces. Alnico magnets manufactured by AM using selective laser melting were also EBSD mapped directly from laser-ablated surfaces, despite the misorientation gradients, porosity, and range of grain sizes that exist as a result of the AM process.…”
Section: Direct Ebsd Imaging From Laser-ablated Surfacesmentioning
confidence: 99%
“…(a) EBSD grain maps collected directly from femtosecond laser-ablated surfaces from an Alnico magnet, 88 shock-loaded tantalum, 85 Inconel 718 and Rene 65 nickel-base superalloys. 86,87 (b) EBSD grain maps collected from femtosecond laser-ablated surfaces of Ti-6Al-4V, 90 a Heusler NiTiSn alloy, 91 Ti-Al and a spot weld on a single-crystal NiAlMo alloy that were all polished with a< 10 glancing-angle FIB beam (30 kV, 65 nA). All data collected with UCSB TriBeam prototype system.…”
Section: Combined Laser Ablation and Glancing-angle Fib Millingmentioning
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
