Effect of post-dynamic recrystallization on microstructure evolution of GH141 superalloy after gradient thermal deformation

The GH141 superalloy ring-rolled parts often face microstructural inhomogeneity during production. This work investigated the effect of post-dynamic recrystallization on the microstructural evolution of GH141 superalloy after gradient thermal deformation to solve the problem of microstructural inhomogeneity. Compression tests involving double cone (DC) samples were conducted at various temperatures to assess the effect of gradient strain on internal grain microstructure variation, which ranged from the rim to the center of the samples. The results demonstrate considerable microstructural inhomogeneity induced by gradient strain in the DC samples. The delay in heat preservation facilitated post-dynamic recrystallization (PDRX) and promoted extensive recrystallization in the DC samples experiencing large gradient strain, which resulted in a homogeneous grain microstructure throughout the samples. During compression at a relatively low temperature, dynamic recrystallization (DRX) was predominantly driven by continuous dynamic recrystallization (CDRX). As the deformation temperature increased, the DRX mechanism changed from CDRX-dominated to being dominated by discontinuous dynamic recrystallization (DDRX). During the delay of the heat preservation process, PDRX was dominated by a static recrystallization mechanism, along with the occurrence of meta-dynamic recrystallization (MDRX) mechanisms. In addition, the PDRX mechanism of twin-induced recrystallization nucleation was observed.