Monitoring and detection of meltpool and spatter regions in laser powder bed fusion of super alloy Inconel 625

Additive manufacturing is being adopted to produce metal parts directly from digital design with applications in automotive, aerospace, and biomedical products. Laser powder bed fusion (LPBF) process is a viable technology for this purpose that utilizes a high-power laser beam which follows layer-to-layer scanning of predefined paths on a metal powder bed. In situ monitoring of LPBF process is essential to detect the localized meltpool, its vicinity, and material spatter around it with a goal to control the health of the meltpool. Among many alternatives, high-fidelity video monitoring can provide cost-effective insights to the on-going process to detect changes in meltpool and its vicinity that can further be integrated into an adaptive control system. For this purpose, a high frame rate camera was employed for in situ viewing of meltpool regions during laser fusion of a super alloy, Inconel 625, powder material to be able to improve the process control capability. The size and shape of the meltpool and the heat affected region detected via in situ viewing represent the sources of information to detect possible anomalies and defects. These acquired video volumes were processed and analysed using statistical process control (SPC) charts. The results indicate that some occurrences of undermelting, overmelting, and material spatter can be detected that can then be correlated to localized defects, delamination, and layer separation.