High-speed imaging and process characterization of coaxial laser metal wire deposition

In this work, coaxial laser metal wire deposition (LMWD) process is studied, with particular attention to defect formation mechanisms and the establishment of stable processing conditions. The coaxial LMWD of AISI 308 stainless steel wire was carried out by a multi-mode fiber laser delivered to an industrial coaxial LMWD deposition head. The continuous mechanical connection with the deposition region requires further attention to the process dynamics, which may alter the deposition precision and continuity. Accordingly, this work presents a systematic analysis of how the defects are formed at single and multiple layer deposition conditions. High-speed imaging is employed to reveal the process dynamics as a diagnostics aid. The process stability is determined initially at single layer condition, providing a correct match between the melting position and rate of the wire. At multiple layer deposition, the thermal load is managed to achieve high-aspect ratio components. At the stable conditions, the process is benchmarked for porosity, surface roughness, and deposition rates.