Dynamic recrystallization behavior of EP741NP alloy during high-temperature deformation

EP741NP Ni-based superalloy is widely used for high-performance rotating components in advanced aeroengines. However, γ′-forming elements increase processing difficulty and significantly affects its microstructure evolution during hot deformation. Here, the dependences of dynamic recrystallization behavior on deformation temperature (T), strain rate ( ε ̇ ) and strain (ε) during compression deformation of EP741NP superalloy are revealed. The dynamic recrystallization degree increases with increasing deformation temperature and strain, while it has a negative correlation with strain rate. The optimized processing parameters are determined as T = 1140 ℃, ε ̇ = 0.001 s - 1 and ε =0.7. Discontinuous and continuous dynamic recrystallization both contribute to the hot deformation of EP741NP superalloy. With increasing deformation temperature (T≥1140 ℃), rising strain ( ε ≥0.5), and decreasing strain rate ( ε ̇ ≤0.01), discontinuous dynamic recrystallization gradually dominates microstructural evolution, which could be attributed to the weakened pinning effect of γ′ phases on dislocation at higher temperatures, enhanced grain boundary bulging at lower strain rates, and higher accumulated stored energy from deformation at larger strain, respectively. The findings provide guidelines for optimizing mechanical processing parameters for Ni-based superalloys with superior mechanical properties. • The DRX degree rises with higher temperature and strain level. • The DRX degree decreases with increasing strain rate. • CDRX and DDRX both contribute to the hot deformation of EP741NP superalloy. • DDRX dominates as temperature and strain rise, and strain rate decreases.