Evolution of Annealing Twins in a Hot Deformed Nickel-Based Superalloy

Abstract

The hot deformation characteristics of a GH4169 superalloy are investigated at the temperature and strain rate ranges of 1193–1313 K and 0.01–1 s−1, respectively, through Gleeble-3500 simulator. The hot deformed microstructures are analyzed by optical microscopy (OM), transmission electron microscopy (TEM), and electron backscattered diffraction (EBSD) technology. The effects of deformation parameters on the features of flow curves and annealing twins are discussed in detail. It is found that the shapes of flow curves are greatly affected by the deformation temperature. Broad peaks appear at low deformation temperatures or high strain rates. In addition, the evolution of annealing twins is significantly sensitive to the deformation degree, temperature, and strain rate. The fraction of annealing twins first decreases and then rises with the added deformation degree. This is because the initial annealing twin characters disappear at the relatively small strains, while the annealing twins rapidly generate with the growth of dynamic recrystallized grains during the subsequent hot deformation. The fraction of annealing twins is relatively high when the deformation temperature is high or the strain rate is low. In addition, the important role of annealing twins on dynamic recrystallization (DRX) behaviors are elucidated. The obvious bulging at initial twin boundaries, and the coherency of annealing twin boundaries with dynamic recrystallized grain boundaries, indicates that annealing twins can motivate the DRX nucleation during the hot deformation.

Modeling Dynamic Recrystallization Behavior in a Novel HIPed P/M Superalloy during High-Temperature Deformation

“…In addition, the X drx increases significantly. Although the DRX grains grow up, the average grain size decreases to 4.39 μm because of the annihilation/rearrangement of dislocations and the migration of GBs [ 42 , 43 , 44 ]. When the true strain is further raised to 0.92 ( Figure 4 c), the number of grains with high GOS values further decreases and the KAM also declines to 0.56°.…”

Hot deformation behavior and constitutive modeling of a cost-effective Al8Cr12Mn25Ni20Fe35 high-entropy alloy

“…15 (b), annealing twins can be observed within the HAGBs, indicated by blue lines. Xia et al [65] linked the annealing twins within the DRX grains to the increased strain, which was promoted by grain boundary migration during DRX. In agreement with another study by Bozzol et al [61], annealing twins were obtained by strain-induced boundary migration (SIBM).…”