Effects of microstructure anisotropy on dynamic fracture behaviors of a selective laser melting nickel-based superalloy

In the study, the crack initiation and propagation behaviors of Ni-based GH3536 manufactured by selective laser melting (SLM) are quantified by the absorbed impact energy and the dynamic crack resistance curves. It is found that the SLM fabricated alloy exhibited slightly lower strength but much higher dynamic fracture toughness along the building direction, compared to those along transverse directions and the hot-rolled counterpart. The microstructure and defects of the SLM GH3536 alloywere characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), electron back-scattered diffraction (EBSD) and micro-computer tomography (μ-CT). Furthermore, the correlation between microstructure anisotropy and dynamic fracture behaviors are explored by the KAM, fractography and crack trajectories analyses. It is concluded that the anisotropy related to dynamic fracture mechanism of GH3536 alloy manufactured by SLM can be attributed to the ‘weakest link’ interface due to the laser melted pool geometry, the grain boundary or dendrite, which is strongly dependent on the relative orientation difference between the building direction and the crack plane. • The obvious anisotropy of SLM GH3536 in terms of tensile properties and fracture toughness was demonstrated. • The characteristic fracture behaviors were quantified by the absorbed impact energy and J -R curves. • The correlation between microstructure anisotropy on tensile and dynamic fracture behaviors were explored.