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The effect of substrate surface preheating on part distortion in laser cladding is investigated through the experimental results of laser deposited Ti–6Al–4V. In situ temperature and distortion measurements were used to monitor the behavior of the substrates before, during, and after deposition. The resulting trends were analyzed, and it was determined that substrate preheating reduces the amount of distortion accumulated in thin substrates but increases the amount of distortion accumulated in thick substrates. Additionally, substrate preheating was found to cause additional distortion of thick substrates during cool-down after processing had finished. The in situ measurements suggest that the stress relaxation of Ti–6Al–4V at elevated temperatures increases the distortion observed in thick substrates, but has minimal effect on distortion in thin substrates.

Through laser-based, directed energy deposition, single-track bead-on-plate clads of Inconel® 718 were deposited onto substrates of the same composition. Postprocessing analyses of the geometry of the single beads were made to assess the effects of changes in processing parameters. Laser power, travel speed, working distance, and initial substrate temperature were varied to alter the shape of the laser deposited material. The resulting geometries were analyzed through metallography and optical profilometry. This study concludes that laser power has the largest effect on bead width, and that working distance has the largest effect on bead height and angle of repose. Additionally, substrate preheating was found to amplify the effects of varying power on bead height and width. Empirical models were developed to describe the geometry of single beads based on chosen processing parameters. These models were compared to optical profilometry measurements for accuracy.

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Single-bead, laser-deposited Inconel® 718 tracks atop substrates of the same composition were studied to ascertain the influence of laser power, processing speed, working distance, and substrate preheat on the fusion zone geometry, microstructure, and hardness. Modifying working distance encompassed both a change in powder flow distribution and beam diameter. Laser power and processing speed linearly affected fusion zone width and area, though laser power was found to have the most significant effect of all processing parameters. Preheating the substrates increased the width of the fusion zone by an average of 16% and led to a more uniform hardness throughout. The fusion zone cross-section was found to morph from semicircular to double-parabolic (wavy) with increasing laser power. This was attributed to surface tension induced Marangoni flow and the influence of surface-activated species on surface tension. The applicability of coupled parameters, including linear heat input and normalized enthalpy were investigated. Given the limited data available on the influence of processing parameters, particularly working distance and substrate temperature, on fusion zone geometry and hardness, results reported here may aid experimentalists and modelers working on cladding and additive manufacturing processes.