Hot deformation behavior and recrystallization mechanism of a novel Ni-based superalloy GH4780

Abstract

Ni-based superalloys serve as critical high-temperature components in advanced aerospace engines, where precise prediction of hot deformation behavior and microstructural evolution is essential for manufacturing process optimization. This study systematically investigates the hot deformation characteristics and dynamic recrystallization (DRX) mechanisms of a novel GH4780 superalloy through thermal compression experiments spanning 1030–1120 °C and strain rates of 0.001–1 s⁻¹. A corrected constitutive model integrating friction, thermal, and strain effects was developed, demonstrating excellent predictability of flow behavior across the tested conditions. Microstructural analysis via electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) reveals that discontinuous dynamic recrystallization (DDRX) dominates the softening process, while twin-induced dynamic recrystallization (TDRX) significantly enhances nucleation at grain boundaries. Continuous dynamic recrystallization (CDRX) functions as a supplementary mechanism active particularly under low-temperature and high-strain-rate conditions. The activation energy (Q) for hot deformation ranges from 427.70 to 476.42 kJ mol⁻¹, with higher values corresponding to enhanced degree of DRX, typically presenting as larger recrystallized areas or grain structures exhibiting both uniform size and homogeneous distribution. These findings provide fundamental insights into the multi-mechanism DRX behavior of GH4780 superalloy, establishing a theoretical basis for optimizing its thermo-mechanical processing parameters.