Mill scale strengthened ABS composite filaments for 3D printing technology

Recycling raw iron oxide mill scale formed on steel slabs during the hot rolling process is one way to reduce operating costs and increase steel mill revenue. This research utilized hot rolling mill by-products to fabricate low-cost sustainable raw material for use in 3D printing technology. Mill scale was recycled as iron oxide powder and used to reinforce 3D-printed acrylonitrile–butadiene–styrene (ABS) matrix composite filaments. Prepared mill scale powder was added to ABS composite filament at up to 1.0 vol% mill scale. Homogeneous fine mill scale particle dispersion in the ABS matrix was validated by 3D-reconstructed images of the cross-sectional composite filament by X-ray micro-computed tomography (μCT). Moreover, the obtained images were further used to generate a finite element (FE) model for describing local stress distributions around the mill scale particles in the ABS matrix and predicted stress–strain curves were compared with the experimental results. High mechanical and thermal properties and printability of mill scale strengthened ABS composite were found for both as-filament and as-printed conditions. The thermal properties and stability of the polymer matrix composite (PMC) filament were similar to pure ABS. Tensile strength and impact absorbed energy of printed ABS composites increased when adding 1.0 vol% mill scale, in which a 45% increase of tensile strength could be reached. After failure, brittle fractures and many air gaps were found on edges of samples correlating well with the raster orientation.