Laser metal deposition strategies for repairing flat and notched substrates made of Ni-based single crystalline superalloys

Laser metal deposition, or laser cladding, has been applied to the repair and manufacture of turbine blades as well as other superalloy components. In some cases, these applications can lower parts manufacturing and maintenance costs, or even increase engine efficiency; therefore, they attract considerable interest from the aerospace industry. However, the single crystalline (SX) repair of Ni-based superalloy parts is still a technology under development. Recent works aimed to understand the solidification phenomena present in a laser-formed melt pool or to achieve SX-depositions through epitaxial solidification computational modelling. Here, to attain high SX-depositions on flat and notched substrates without the need of such sophisticated methods, a previously developed design of experiments (DoE) for laser remelting was used to produce SX clad tracks. New data related to this DoE is presented, describing its characteristics and possible improvement. Further on, a remolten clad track extracted from the DoE was used as a basis to three cladding strategies applied on flat (010) substrates. From such depositions, one strategy was chosen to also be applied on a (110) substrate, yielding insights on the interaction between substrate orientation, cladding strategy and track parametrization adequacy. The depositions were evaluated through EBSD mapping and profiling, as well as OM observation. Finally, the clad tracks’ disposition of a successful SX-deposition was used to determine a notch profile. The notch profile was then machined into a substrate, simulating a crack repair, and filled accordingly. This extrapolation from flat to notch was based on simple geometrical considerations and resulted in a SX notch fill. Therefore, showing evidence that the sequence of considerations taken are a promising approach to define notch geometry for SX-repair. The cladding strategies evaluated, the verified DoE and the approach taken for notch filling, may be of use to researchers and engineers when planning more sophisticated procedures that aim the repair of Ni-based SX components.