In Situ Monitoring and Quality Evaluation of the Powder Bed Fusion Process of IN718 Alloy Powder

Predicting the melt pool temperature of each melt track is a critical scientific challenge in monitoring laser powder bed fusion of metal powders in additive manufacturing. This study introduces a methodology for processing melt pool temperature data acquired with an infrared camera. The approach leverages measurement uncertainty concepts and analytical expressions that describe the Kalman filter algorithm. If the melting temperature of the metal powder is too low, it results in lack of fusion and the formation of porous, low-density components. Conversely, excessively high temperatures cause material evaporation and generate high recoil pressure. By applying this methodology, which uses Kalman filtering to determine the temperature of each melt track, the study allows for the examination of track temperatures across different laser power (LP) and enables the control of the laser powder bed fusion process within the specified limits of expanded measurement uncertainty. Experimental results on the laser melting of IN718 alloy powder reveal that optimal, complete melting occurs at an average temperature of 1455 °C ± 105 °C at a LP of 285 W. The proposed classification of laser melting quality indicators for the IN718 alloy powder facilitates the generation of control signals to adjust LP when the permissible expanded uncertainty limits are exceeded, ensuring high-quality melt pool conditions for the alloy powder.