Dynamic recovery observed in distinct grains within a polycrystalline nickel-based superalloy during cyclic high temperature fatigue via high energy X-ray diffraction microscopy

A review of microstructure phenomena during manufacture of polycrystalline Ni-based superalloys

“…The conditions that favour each of these competing phenomena can be visualised through the contour plots in Figure 7, which have been plotted using data from multiple studies [32,44,45]. It must be noted that there is limited data for conditions where DRV is dominant; hence this region has been estimated based on qualitative findings [46]. As well as limited data, often studies are published with incomplete data, which limits their use for cross-referencing with other results.…”

“…Nonetheless, it would be useful for future studies to examine conditions that favour DRV to develop a more comprehensive view of microstructure evolution during forging. A study by Gustafson et al [46] observed DRV in the low solvus high refractory (LSHR) P/M superalloy during cyclic high-temperature fatigue between 460 and 770°C at low strains of 0.012. While this study provides a good starting point for further research, analysis of results may be enhanced by including temperatures as a fraction of the material's T m to allow for improved comparison between different alloys.…”

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Figure 7 Contour plots of % RX grains as a function of forging temperature and strain rate at (a) low strains 0.1–0.3 and (b) a higher strain 0.7, plotted using data of René 65, an experimental superalloy and RR1000 from [32,44,45]. Region of DRV has been estimated using qualitative findings [46]. DRX*: Now thought to be post-dynamic recrystallisation as discussed in Section 5.

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