Microstructural Characterization of Spray Formed FGH4095 Superalloy During Hot Deformation

In order to study the hot workability and to optimize the processing parameters for spray formed FGH4095 superalloy, thermal compression tests for spray formed FGH4095 superalloy have been finished by using a Gleeble 1500 thermal simulated test machine at the strain rates of 0.01-10.0 s-1 and temperatures of 1 050-1 140 ℃. The effects of strain rate and deformation temperature on the true stress-true strain curves and microstructure evolution were investigated. The results show that the generation of dynamic recrystallization (DRX) depends sensitively on deformation temperature. When the temperature was lower than 1 080 ℃, long and narrow necklace grains were shown in the microstructure. When the temperature increased to 1 140 ℃, new recrystallization grains were generated. The size and shape of γ’ precipitates in the grains have a very important effect as factors of hindering sufficient migration of dislocations on plastic deformation. The result of thermal processing map is in accord with the microstructure observation, and the best material thermal processing temperature is above 1 128 ℃.