Hot tensile testing was adopted over the temperature range of 850°C–1150°C and at strain rates of 0.001 s^–1–1 s^–1 to study the hot ductility of Incoloy 901. Hot ductility of the material was optimized in range of 950°C–1050°C and descended at either higher or lower temperatures. Dynamic recrystallization was the reason for the improvement of ductility at high temperatures. At lower temperatures, e.g. 850°C, dynamic precipitation of intermetallic phases could effectively inhibit dynamic recrystallization and resulted in poor hot ductility.
At very high temperatures, e.g. 1150°C, the hot ductility drop was due to the decohesion of particles/matrix interfaces. The insensitivity of material to flow localization was understood from the monotonic increase of the strain rate sensitivity over the studied temperature range. The peak strain of the material unexpectedly increased with increasing temperature up to 1050°C and then decreased at higher temperatures. These results accounted for the possibility of dynamic precipitation of intermetallics at temperatures below 1050°C and thereby delaying dynamic recrystallization. The hyperbolic sine constitutive equation was used to describe the dependence of tensile stress on deformation temperature and strain rate and the corresponding material constants were determined. The average apparent activation energy for the initiation of dynamic recrystallization was determined as 359 kJ mol^–1.