Study on the microstructure evolution and dynamic recrystallization mechanism of selective laser melted Inconel 718 alloy during hot deformation

Abstract

In this work, isothermal compression testing, electron back scattered diffraction (EBSD) technology and transmission electron microscope (TEM) were used to investigate the hot deformation behavior, microstructure evolution, and dynamic recrystallization (DRX) behavior of selective laser melted (SLM) 718 alloy. The results show that the deformation condition has significant impact on the flow behavior and DRX grain. With the increase of the deformation temperature or the decrease of the strain rate, the volume fraction and average size of DRX grains show an increasing trend. The DRX mechanism of SLM 718 alloy includes discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX), in which DDRX is characterized by initial grain boundary and regenerated grain boundary bulging. CDRX occurs inside the grain, characterized by progressive subgrain rotation and homogeneous misorientation increase.