Abstract:Forging is the key forming process for producing advanced aero-engine powder turbine disks. The microstructure of as-extruded alloy mostly depends on the chemical composition of alloy and extrusion processing parameters. Average grain size number is greater than 13 for the novel powder nickel-based superalloy FGH4113A after hot extrusion. As-extruded alloy has two phases microstructure of γ+γ". Fine homogenization two phases microstructure makes it possible to broaden isothermal forging processing window. In this study, Gleeble hot compression experiments for as-extruded FGH4113A alloy with ultrafine grains were carried out at temperatures of 1000, 1040, 1080, 1120℃ and strain rates of 0.001, 0.01, 0.1s-1. Height reduction is 60% for samples under all experiment conditions. The results show that no crack was found on the surface of alloy samples under all experiment conditions, suggesting as-extruded FGH4113A alloy with ultrafine grains has a wide isothermal forging process window. The average activation energy for the alloy is 515.375kJ/mol. True stress-true strain curves show steady flow characteristic for samples with slow strain rate (0.001s-1) and the change from work hardening to recrystallization softening for samples with fast strain rate (0.1s-1). γ" is sensitive to temperature. Recrystallization grains grow obviously at high deformation temperature due to the large amount of dissolution of γ". Furthermore, the study shows that the main recrystallization way is discontinuous dynamic recrystallization for as-extruded FGH4113A alloy with ultrafine grains. This study offers experiment evidence for designing forging processing of the as-extruded FGH4113A alloy with ultrafine grains.