Abstract：Nickel-based powder metallurgy (PM) superalloys were widely used to manufacture the components in
gas turbine engines owing to their outstanding mechanical properties at extremely high temperatures. In order to
design a new generation aircraft engine with a higher thrust-weight ratio and satisfy the performance requirements,
a fourth generation PM superalloy has been studying worldwide. The alloy FGH4102 in this study was a newly
designed fourth generation PM superalloy, which exhibited excellent high- temperature stress rupture and creep
properties compared with the previous three generations' PM superalloys, FGH4095, FGH4096, and FGH4098.
This work aims to study the thermal deformation behavior of hot isostatic pressured (HIPed) alloy under different
deformation conditions and provided a reference for subsequent extrusion and isothermal forging process parameter
design. The hot deformation behavior of HIPed alloy FGH4102 was studied by using isothermal simulation compression experiments. The effects of different deformation conditions (strain rate, strain temperature, and strain
variables) on the volume fraction and grain size of dynamic recrystallization were analyzed, and the role of γ 'phase
in dynamic recrystallization was discussed. The results show that the dynamic recrystallization of HIPed alloy
FGH4102 occurs in different degrees within the range of deformation parameters. When the strain exceeds the critical
strain, dynamic recrystallization takes place first near the original grain boundary. With the increase of strain,
dynamic recrystallization grains gradually replace original coarse grains, and the volume fraction of dynamic recrystallization
keeps increasing. After low temperature and high strain rate deformation, the dynamic recrystallization
of the alloy is sufficient, and the grain size becomes smaller than the previous. The increase of deformation
temperature and strain rate decreases the nucleation rate of dynamic recrystallization and increases the grain size of
recrystallization. After the deformation at 1 140 ℃, the grain grows significantly, which leads to the deterioration
of the hot working property of the alloy, and the sample is prone to cracking. When deformed in the γ+γ′ two-phase
region, the fine secondary γ′ phases dispersed in the matrix have an inhibitory effect on dynamic recrystallization.
As the size of the initial γ′ phase increases, the inhibition of recrystallization is gradually weakened. As for the
HIPed alloy FGH4102, the micron-sized γ′ phases can promote dynamic recrystallization during hot deformation.
When deformed at low temperature and high strain rate, γ′ phases promote dynamic recrystallization nucleation,
and recrystallized grains are relatively small. When deformed at high temperature and low strain rate, grain growth
gradually dominates. Moreover, the recrystallized grain sizes are comparatively large.
2022, Vol. 32 
