Thermal processing behaviour and microstructural evolution of high W and high γ′ content extruded nickel-based powder metallurgy superalloy FGH4109

Nickel-based powder metallurgy superalloys with high W and high gamma ' content exhibit excellent high-temperature properties, but their high deformation resistance poses significant challenges for hot processing. In this study, the hot compression behaviour of an extruded nickel-based powder superalloy FGH4109 with high W (6.1%) and high gamma ' phase contents (60%) was systematically investigated at temperatures ranging from 1060 degrees C similar to 1140 degrees C, strain rates from 0.001 s(-1) similar to 1 s(-1), and maximum true strains of 0.7. Combined with the hot working map and the microstructure evolution in different hot working zones, the optimal hot working window for the alloy was determined to be in the temperature range of 1060 degrees C similar to 1140 degrees C and strain rates of 0.001 s(-1) similar to 0.012 s(-1), where the power dissipation efficiency eta was greater than 0.5, and the dominant deformation mechanism was discontinuous dynamic recrystallisation.