Assessment of the post-dynamic recrystallization effects on the overall dynamic recrystallization kinetics in a Ni-base superalloy

Understanding the role of microconstituents, viz., precipitates, and carbides, on dynamic recrystallization (DRX) and on post-dynamic recrystallization (PDRX) is essential to obtain a uniform microstructure with desirable grain size during hot deformation. Thus, the present study was taken up to address the role of carbides on DRX as well as on the PDRXcharacteristics of a Ni-base superalloy XH55 (Ni-17Cr-12Fe-9Mo-2 Nb-1.8Al-0.04 C). Uniaxial hot compression tests were conducted in the temperature range of 950-1100 degrees C and at a constant strain rate of 10(-1) s(-1) on the peak-aged specimens. The evolution of DRX without and with post-deformation hold for 15 s was correlated with the flow softening mechanisms across the tested temperature range. Besides, the PDRX fraction and its evolution with temperature was estimated from the electron backscattered diffraction data while using the denoising filters and a grain level misorientation parameter. Further, intermittent post-deformation microstructural characterization was carried out on the specimens deformed at 1050 degrees C to understand the role of carbides in the initial stages of DRX and PDRX. Overall, the present study illustrates that carbides have inhibited the DRX kinetics in the initial stage, i.e., at low strains (epsilon < 0.40). Whereas, at higher strains (epsilon > 0.40), the role of carbides is limited in inhibiting the growth of the recrystallized (DRX and PDRX) grains present in their vicinity. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the role of carbides in the dynamic recrystallization and post-dynamic recrystallization of a Ni-base superalloy. It is found that carbides inhibit the kinetics of recrystallization in the initial stage, but have limited inhibitory effect on the growth of recrystallized grains at higher strains.