Origin of Anisotropic Plasticity and Dynamic Recrystallization-Like Deformation Behavior of Laser Powder Bed Fusion Inconel 625 at Elevated Temperature

This work revealed the origin of dynamic recrystallization-like deformation behavior and anisotropy in the mechanical properties at elevated temperature of laser powder bed fusion (LPBF) processed Inconel 625 specimens along horizontal (HOR) and vertical (VER) directions with respect to build platform. Typical grains along building direction were observed in both direction specimens. Rotation of elongated grains was evidenced by the movement of low angle rotation axes within grains along <001>~<111> line during deformation. Consequently, geometric hardening and softening accompanied with grain rotation was responsible for the dynamic recrystallization-like flow stress fluctuation during deformation. Moreover, variation of rotation axes between grains is observed in HOR specimen, suggesting occurrence of compatible deformation between grains is needed. However, intergranular cracks were observed in HOR specimen, demonstrating grain boundaries embrittlement. Hence, the decrease of plasticity of HOR specimen is originated from incompatible grain deformation when deformation was perpendicular to grain boundaries.