A 5 kW continuous wave fiber laser welding system was used to deposit INCONEL® alloy 718 (IN718) on service-exposed IN718 parent metal (PM) substrates using filler wire addition. The microstructure of the deposits was characterized in the fully heat treated condition. The service-exposed IN718 PM and the direct laser deposited (DLD) specimens were then evaluated through room temperature tensile testing. The yield and tensile strengths were well above the minimum values, as defined in the aerospace specifications AMS 5596K and 5663M. However, the ductility at room temperature of the DLD and DLD-PM samples was slightly lower than that specified in AMS 5596K and 5663M. The tensile fracture surfaces of the service-exposed IN718 PM, DLD, and DLD-PM specimens were analyzed using scanning electron microscopy (SEM), and the tensile failure mechanisms are discussed in detail, particularly for the important roles of the secondary particles (MC carbides) and intermetallics (platelet Ni3Nb-δ and Laves phases).
Journal of Materials Research29, no. 17 (14 September 2014): 2006–2020.