The Effect of Powder on Cooling Rate and Melt Pool Length Measurements Using In-Situ Thermographic Techniques

High-speed thermal cameras enable in situ measurement of the temperatures in and around melt pools generated during powder bed fusion processes. These measurements can be used to validate models, to monitor the process, and to understand the microstructure formed during the process. Unfortunately, pre-placed powder layers complicate the measurement due to spatter and irregular surfaces that impact emissivity. The objective of this work is to present high speed thermographic measurements of single and multiple scan tracks on substrates with and without pre-placed powder and to analyze and compare the impacts of powder on melt pool length and cooling rate measurements.