Influence of Deformation Rate on Nucleation and Growth of Recrystallized Grains during Hot Deformation of Nickel-Based Powder Superalloys

Abstract High temperature uniaxial compression deformation test was carried out on nickel-based powder superalloy FGH96 alloy by thermal processing simulation test machine, and the relationship between grain boundary characteristics and nucleation mechanism of recrystallized grains, growth characteristics of recrystallized cores and related dynamic softening mechanisms was studied. According to the correlation and evolution law of grains, combined with the change trend of grain orientation during the deformation process, the recrystallization behavior characteristics of the grains with special orientation generated during the deformation process were analyzed. When the deformation temperature is 1070 °C, the evolution rules of the substructure grain boundaries with an orientation difference of less than 10° are different under different deformation rate conditions, which indicates that the dynamic softening mechanism of FGH96 alloy is slightly different with the increase of deformation rate. There are different. With the increase of the deformation rate, the nucleation mechanism induced by Σ3 twinning gradually replaced the nucleation mechanism of continuous subgrain rotation and coarsening, and the grain growth rate gradually slowed down.