Fiber Laser Deposition of Aerospace Superalloys

Fiber Laser Deposition of Aerospace Superalloys Precipitation-hardenable nickel-iron base superalloys, such as Inconel 718, are widely used for aerospace and nuclear components due to their excellent combination of corrosion resistance, oxidation resistance, tensile and creep properties, as well as good weldability due to microstructure stability and resistance to strain-age cracking at elevated temperatures up to 650°C. In this work, a continuous wave 5 kW fibre laser welding system was used to weld deposit a Ni-base superalloy using filler wire and powder feed sources with compositions that matched the parent metal. The single-bead, multi-bead, and multi-layer weld deposits were characterized in terms of the macrostructure, defects, microstructure and mechanical properties. Particularly, for the mechanical properties, three material conditions, namely as-serviced Parent Metal (PM), Direct Laser Deposits (DLD) and PM-DLD were evaluated by hardness, tensile (room and elevated temperature), creep, smooth and notch rupture tension, and fatigue testing. The mechanical properties obtained were then compared to existing aerospace materials specifications. By using optimized laser processing parameters, high quality deposits (minor porosity and limited weld metal liquation cracks) with good mechanical properties are realizable. The successful development of the direct laser deposition process using wire and powder feeding indicates the marked potential of employing the fiber laser technology to repair and manufacture aerospace superalloy components.