3D extrusion printing of 304 stainless steel/polypropylene composites and sintering process optimization

Screw extrusion 3D printing in the low-cost preparation of high-quality metal products, which offers an edge over fused deposition molding (FDM) and laser-based additive manufacturing. In this study, spherical 304 stainless steel (SS304) micronized powder and polypropylene (PP) pellets were used as raw materials to manufacture composite samples of SS304 with a mass fraction of up to 90 wt%. After high-temperature heat treatment, metal samples with good qualities were obtained. The influence of 3D printing paths and heat treatment processes on the microstructure and mechanical properties of printed parts were studied. The results reveal that the samples printed using 27°/152° cross paths achieved a relative density with 95.78% and a tensile strength with 484 MPa after 6 h of sintering at 1280 °C at a pre-debinding rate with 60%. The overall performance is on par with components created using metal injection techniques (MIM), and this work provides the novel proposals for the production of metal parts using affordable 3D printing.