Determination of True Temperature in Selective Laser Melting of Metal Powder Using Infrared Camera

Abstract

The objective of this study is to restore the true temperature in during the process of Selective Laser Melting (SLM) of metal powder (in the present case INOX 316L), that is the actual problem in laser assisted additive technologies. To meet this objective, at the first stage, the temperature was measured on the surface of metal substrate INOX 304L without a powder layer. Based on the results of studies the method of temperature measurementof the molten pool surface on metallic plates and during melting of metal powder layer, that were exposed to laser radiation, using an infrared camera (IR), in the present case FLIR Phoenix RDAS TM, was proposed. To restore the true temperature based on the brightness temperature values measured by IR camera, the results of temperature measurements were compared with the width of the molten track on the surface of the plate in the absence of powder. In case of SLM, the results of IR camera measurements were compared with the width of a welded track (bead). The true temperature profiles and temperature gradients values were determined along the axis of the laser beam for melting of plates without powder. In the case of powder melting, the developed method allows to determine the influence of several key SLM parameters on the molten pool shape.