This contribution investigates the emissivity of Inconel 718 in the context of laser-based Directed Energy Deposition (DED), focusing on the impact of surface finish variations resultant from additive manufacturing techniques and the challenges it poses when monitoring the process via thermal imaging. We perform directional spectral measurements from 100 $$^{\circ }$$ ∘ C to 900 $$^{\circ }$$ ∘ C in high vacuum using a custom-made emissometer and analyze the differences between samples synthesized via casting and laser metal deposition. The data are also treated to obtain total hemispherical emissivity values and to compare them to literature data. Finally, as emissivity is the only input data that can be modified in thermographic cameras to calculate the temperature, we perform a temperature calculation error analysis to clarify the conditions and the emissivity input data under which the infrared cameras should operate in these additive manufacturing processes to make the temperature measurement more reliable.

This contribution investigates the emissivity of Inconel 718 in the context of laser metal deposition, focusing on the impact of surface finish variations resultant from additive manufacturing techniques and the challenges it poses when monitoring the process via thermal imaging. Our methodology involves examining the emissivity of Inconel 718 samples produced through laser metal deposition, with a particular focus on the Mid-Wave Infrared and Long-Wave Infrared spectral ranges, common in industrial-grade thermal cameras. We perform directional spectral measurements from 100 °C to 900 °C in a controlled atmosphere using a custom-made emissometer and analyze the differences between samples synthesized via casting and laser metal deposition. The data were also treated to obtain total hemispherical emissivity values and to compare them with the literature data. Finally, we perform a temperature calculation error analysis to clarify the conditions and emissivity input data under which infrared cameras should operate in these additive manufacturing processes.