Superalloy Radiative Heat Transfer in Additive Manufacturing

Direct Laser Metal Sintering (DLMS) is a layer-by layer additive manufacturing process using a high power focused source such a laser or electron beam. As the metal powder melts, the melt pool experiences non-equilibrium thermalization processes involving convection, evaporation, plasma creation and radiative cooling, expected to be most important at high temperature. Developing a fundamental understanding of the melt pool cooling rate through the radiative cooling is invaluable to controlling microstructure of the final product. In DLMS a high energy melting source is focused to a small spot size on the build plate and travels across the powder layer at a high velocity, all of which parameters make in-situ measurements of melt pool temperature from radiative cooling difficult. We discuss approaches to spatially resolved temperature analysis of the DLMS melt pool as well as a combined experimental and theoretical optical property investigation of superalloys typically used in DLMS.