Thermal Deformation Characteristics and Dynamic Recrystallization Mechanism of Incoloy 800H Alloy under Different Deformations

Abstract

Incoloy 800H alloy has excellent high‐temperature mechanical properties and broad application prospects. However, the dynamic recrystallization (DRX) behavior of this alloy at different deformations has been little studied. The thermal deformation characteristics and DRX mechanisms of Incoloy 800H alloy are studied by thermal compression tests. Quantitative analysis of grain size, DRX fraction, misorientation distribution, and twin boundaries under different deformation degrees is conducted using electron‐backscattered diffraction. Furthermore, the evolution characteristics of dislocations and grains are observed through transmission electron microscopy. It is found that the proportion of DRX improves with increasing deformation significantly. In the DRX process, discontinuous DRX (DDRX) is the main nucleation mechanism, while continuous DRX (CDRX) serves as an auxiliary nucleation mechanism. As the deformation increases, the CDRX + DDRX mechanisms can also be observed simultaneously in the high‐density dislocation region near the grain boundary. In addition, the ratio of ∑3 boundaries first decreases and then increases as the deformation increases. The initial twins gradually disappear due to the increase in deformation, and new twins are formed within the DRX grains. Twins can promote grain boundary bulging, provide more nucleation sites for DRX, and have a significant promoting effect on DRX.