Advanced Repairs of Metal Parts through Laser-Directed Energy Deposition: A Practical Review of Industrial Use Cases

This review offers a practical and systematic overview of laser-directed energy deposition (L-DED) as a technological method for repairing metal components by injecting filler material or applying coatings. It transforms worn parts into reusable ones, restoring their functionality and extending their lifespan. The integration of repair processes is crucial for meeting the target of increasing material reuse by 30% over the next five years, supporting the transition toward a circular economy. The review delves into the foundational principles and applications of additive manufacturing within the repair and restoration sectors. It outlines various L-DED configurations utilized in industry, focusing on the processes and materials involved in repair, while addressing potential anomalies related to material usage. It also explores several industrial applications, highlighting challenges encountered in case studies from the aerospace, automotive, marine, manufacturing, and oil and gas industries. L-DED’s versatility in additive manufacturing is noted, as it accommodates complex geometries and is often integrated with subtractive processes as part of hybrid manufacturing, requiring additional post-processing steps such as heat treatment and hot isostatic pressing. Building on this foundation, this review contributes three distinct advances: (i) a material-structured synthesis of L-DED repair performance that distinguishes between laboratory investigations and industrial implementations across steels, titanium, nickel, cobalt, and aluminum systems; (ii) a comparative framework connecting wire-fed and powder-fed L-DED to conventional restoration techniques including tungsten inert gas welding, plasma transferred arc welding, high-velocity oxy-fuel coating, and electron beam repair, highlighting their trade-offs in rate, resolution, and defect control; and (iii) an integrated outlook on post-processing, qualification, and sustainability, consolidating data from recent case studies to quantify energy efficiency, material utilization, and environmental benefits. Together, these insights offer a data-driven perspective on the technological readiness and sustainability of L-DED for reliable and resource-efficient component repair.