Influence of fluxing agent on the quality of recycled Aluminium billets

Sammanfattning: The quality of aluminium cast billets is highly dependent on the cleanliness of the material. Hydro Extruded Solutions are casting billets in Sjunnen that are delivered for extrusion within the same company. In order to produce extruded profiles of high quality and also maintain the pressing tools, it is a good method to keep the billets as free from inclusions as possible. A fluxing agent in form of salt compounds is used to purify the material during melting, but also to protect it from further oxidation. Another task of fluxing agents is to minimize the aluminium amount in the dross phase. The purpose of this project was to investigate if the fluxing agent that is used by the cast house is having any impact on the quality of the billets. Therefore, for that purpose, samples with a variating amount of fluxing agent were processed by the cast house in order to be investigated. These samples were investigated with the Optical Microscopy-method in order to determine the area fraction of non-metallic inclusions inside them. The results did not reveal any significant difference in the quality of the different samples since most samples obtained a low OM-index after the investigation. That can be explained by the type of scrap that was used since new scrap is usually very clean and contains smaller amounts of inclusions.