Determination of the thermal contact resistance at the solid–powder interface in laser powder bed fusion manufacturing of stainless steel

Among various additive manufacturing (AM) methods, powder bed fusion–laser beam/metal (PBF-LB/M) stands out due to its rapid prototyping capabilities and design flexibility. The simulation of the PBF-LB/M process is receiving growing attention from both the scientific community and industry with the goal of optimizing process parameters, broadening the range of usable materials, or realizing in-situ heat treatments. A deeper understanding of the dynamic heat balance during the PBF-LB/M process, particularly the heat transfer between the part and the surrounding powder during manufacturing, has become an indispensable factor. This study investigates the thermal contact resistance between solid and powders using DIN EN 1.4404 as a model material, an austenitic stainless steel selected for its widespread use in PBF-LB/M and its favorable high-temperature properties. A novel ceramic sample holder is developed that can combine solid and powder materials to create a contact pair as a measurement system, thereby minimizing the influence on the results. By measuring the time–temperature response curves of solid–powder contact pairs after heating at different temperatures using the laser-flash method, the response curves were analyzed using two methods: a mathematical analytical method and a finite element simulation method to determine the thermal contact resistance. The two employed methods can efficiently describe thermal contact resistance and are well-suited for application in numerical simulations.