An integrated experimental and modeling approach to mitigate defects in multi-layer bronze HSLC

The application of high-speed laser cladding (HSLC) to multi-layer deposition is hindered by interlayer defects, as the powder stream attenuates a significant fraction of the laser power reaching the previous layer. This study investigates the origin of these defects, explores mitigation strategies, and proposes an integrated experimental and analytical methodology to support physically informed multi-layer HSLC process development. Three bilayer deposition strategies were evaluated: surface preparation via laser remelting, laser power adaptation, and a combined approach. At low deposition power on rough surfaces, partial filling of surface asperities keeps layers attached through mechanical interlocking but leaves seam lines and lack-of-fusion defects. Increasing deposition power on rough surfaces improves interlayer continuity, but promotes spherical pore formation. Surface pre-smoothing removes the interlocking potential, causing sharp delamination at insufficient second-layer power. Combining pre-smoothing with moderately increased deposition power suppresses visible lack-of-fusion and delamination. This strategy was applied to produce a four-layer proof-of-concept demonstrator. An adapted 1D heat conduction model was fitted to experimental remelting depth data. By correlating remelting thresholds from the fitted model with experimental bilayer results, an effective attenuation of ∼ 63% was estimated. This study supports multi-layer HSLC process development by shifting from trial-and-error toward a more physically informed approach.