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

The GH141 superalloy ring-rolled parts often have the problem of microstructure inhomogeneity during the production process. This work studied the effect of post-dynamic recrystallization on microstructure evolution of GH141 superalloy after gradient thermal deformation to solve the problem of microstructure inhomogeneity. Compression tests using double cone (DC) samples were conducted at different temperatures to assess the impact of gradient strain on internal grain microstructure variation, ranging from the rim to the center of sample. The results demonstrated significant microstructural inhomogeneity induced by gradient strain in the DC samples. While delaying heat preservation, which facilitated post-dynamic recrystallization (PDRX), promoted extensive recrystallization in the DC samples experiencing large gradient strain, resulting in a homogeneous grain microstructure throughout the samples. When compressed 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 being dominated by CDRX to discontinuous dynamic recrystallization (DDRX). During the delaying heat preservation process, PDRX was dominated by static recrystallization (SRX) mechanism and meta-dynamic recrystallization (MDRX) mechanism occurred. In addition, the PDRX mechanism of twin-induced recrystallization nucleation was also observed.