Abstract:Based on the Gleeble thermal compression simulation tester, the hot deformation behavior of the homogenized GH4975 superalloy was investigated at strain rates of 0.1 and 1 s–1 with deformation temperature ranging from 1140 ℃ to 1200 ℃. EBSD and SEM were used to observe the microstructure evolution of the homogenized alloy to study the dynamic recrystallization (DRX) mechanism of GH4975 superalloy. The results show that the main DRX mechanism of GH4975 superalloy at low temperature is discontinuous dynamic recrystallization (DDRX) at grain boundaries. As the temperature increases, the mechanism gradually transitions to particle stimulated nucleation, where secondary phase particles promote the nucleation of new grains. This evolution is associated with the morphology and distribution of the precipitates. In the GH4975 superalloy, the γ′ phase promotes DRX. As the deformation temperature increases, the γ′ phase partially dissolves back into the matrix, and the sparsely distributed γ′ phase contributes to a well-developed dynamically recrystallized grain structure. Additionally, the surfaces of the (γ+γ′) eutectic phase can serve as nucleation sites for recrystallization, thereby further promoting DRX.