Experimental investigations on the influence of temperature for Laser Metal Deposition with lateral Inconel 718 wire feeding

In the present work, the thermal history influence on Inconel 718 thin-wall structures fabricated by wire-based Laser Metal Deposition (LMD-w) was analyzed. To perform the depositions, a novel processing head with wire force and gas nozzle temperature monitoring was employed. Based on the thermal radiation a temperature threshold for a stable process could be defined. General process trends and typical defects as cracks, pores and lack of fusion are also discussed. Additionally, Scanning Electron Microscope (SEM) images and Energy Dispersive Spectroscopy (EDS) were employed to verify the influences of different cooling rates and the deposition strategy on the microstructure. Finally, to verify the resulting mechanical properties, hardness measurements were performed on each sample. It was found that, for thin-wall fabrication by LMD-w, heat accumulation can adversely affect the build-up. Therefore, cooling of interlayers is suggested as a strategy to mitigate such a problem.