Hot Deformation Behavior and Microstructure Evolution of a Novel Hot Extruded Nickel-Based Superalloy FGH4113A

Abstract:

To investigate hot working properties and to control microstructure of the extruded novel nickel-based superalloy FGH4113A, the thermal deformation behavior and microstructure characteristics were studied using Gleeble thermal compressing machine, OM, SEM, and EBSD. Hot deformation experiments were conducted within the temperature of 1050–1150 ℃ and strain rate of 0.001–0.1 s^–1. The results indicate that the grain size of extruded FGH4113A superalloy increases after holding at 1150 ℃. Deformation temperature and strain rate have a significant impact on the deformation flow stress and microstructure evolution. It is recommended for the extruded superalloy to undergo thermal deformation at temperature of 1080–1100 ℃ and strain rate of 0.001–0.01 s^–1 within the γ+γ′ microduplex region. After deformation under these conditions, grains are fully recrystallized and size distribution is uniform, with average size controlled within 5 μm. The residual dislocation density within the grain is small, and the misorientation differences are not significant. Recrystallized grain and deformed original grain can be distinguished from multiple dimensions such as LAM, GOS, and IPF.