Cracking Mechanism in E-Beam 3D-Printed DZ125 Ni-based Superalloys

Directionally solidified Ni-based superalloys are extensively employed to manufacture turbine blades due to their outstanding high-temperature mechanical properties. To reduce overall costs, repairing techniques are highly demanded to restored the shape and properties of damaged turbine blades. In this study, as a surrogate for the repair process, DZ125 Ni-based superalloys were grown epitaxially with the electron beam powder bed fusion 3D-printing method on a base metal with the same chemical composition. Cracks are detected within the printed part, always along the high-angle grain boundaries and roughly parallel to the building direction. The cracks are identified to be liquation cracks, and the thermal cycling effects are proved to play an important role in crack initiation and propagation. The knowledge gained from this work provides valuable insights towards 3D-printing strategy development to obtain crack-free directionally solidified superalloys.