Repair of a Complex Ti-6Al-4V Groove by Coaxial Wire Laser Metal Deposition: Process Window, Tensile, and Very-High-Cycle Fatigue Evaluation

Ti-6Al-4V has seen widespread adoption in the aerospace industry due to its advantageous material properties, but the alloy is costly to produce with vulnerable supply chains. Repair and remanufacture offer economic and environmental benefits over scrapping components. Powder-based additive-manufacturing processes have been investigated; however, coaxial wire laser metal deposition (LMD) remains understudied in repair scenarios, and the transfer of planar process parameters to inclined geometries for complex repairs has not been established. This paper identifies a process window for 1.2 mm Ti-6Al-4V wire and applies the parameters to repair a trapezoidal groove. Tensile and fatigue properties are evaluated, and fractography is conducted using optical and scanning electron microscopy. Findings show the transfer from planar to inclined geometry induces evolving geometric and thermal boundary conditions, including underbuilding and thermal accumulation. Nonetheless, the repair exhibited a yield strength of 868.2 MPa, an ultimate tensile strength of 920.5 MPa, and an elongation of 8.9%. Moreover, UFT revealed a fatigue performance of the repairs that was consistent with heat-treated SLM materials. Fractographic analysis revealed triangular defects and feedstock contamination that contribute to reduced repair properties. As such, this paper demonstrated that coaxial wire-LMD can be used to deposit material into complex geometries, but a complete, defect free repair was not achieved.