Investigation of the in situ thermal conductivity and absorption behavior of nanocomposite powder materials in laser powder bed fusion processes

Abstract

One of the AM processes for direct manufacturing of metallic components is powder bed fusion of metals using a laser beam system (PBF-LB/M), in which metallic powders are molten and solidified in a layer upon layer manner by a focused laser beam. In recent years, the focus has initially been on increasing the efficiency of the systems itself. However, the modification of standard AM metal alloys using nanoparticles offers the possibility to improve the PBF-LB/M-process concerning its process efficiency and actual densification and thermal conductivity. In this work, a methodology for an in-situ investigation of the thermal conductivity as well as the reflectance behavior of metallic powder materials during the PBF-LB/M-process is established. The powder material stainless steel 1.4404 was coated with different nanoparticles (few-layer graphene (FLG), silicon carbide (SiC)) and processed in a standardized build process. As a result, the reflectance rate of all modified materials could be increased. Besides, the thermal conductivity of the material is attested to be a decisive and influencing factor for the quality of the final component. Thus, an improved relative density was achieved using the FLG/1.4404 and SiC/1.4404 (1 vol%) due to the increased thermal conductivity of the material. Also significant defects in the cross section were visible at SiC/1.4404 (4 vol%).