Experimental analysis of four powder recycling strategies for 3D printing: tensile test, powder size distribution, SEM, powder cost and mass analysis

Four distinct powder recycling strategies were evaluated to identify the most sustainable approach for reusing Ti6Al4V alloy powder in 3D printing. Strategies A and B incorporated continuous mixing of recycled and additional powder, while Strategies C and D reused powder without proper mixing. The cost and mass of recycled powder were tracked across 1 to 50 printing cycles, with Strategy A generating the highest powder waste despite supporting a similar number of cycles. Tensile bars were produced in each cycle to assess ultimate tensile strength (UTS), microstructure, particle size distribution, and porosity. Strategy C (reusing powder without mixing) resulted in the lowest mechanical strength and the greatest powder degradation, including extensive particle agglomeration and surface satellites. Although mixing strategies (A and B) generated more waste, they effectively minimized porosity and maintained superior mechanical properties over repeated cycles. The findings demonstrate that mixing fresh powder into the recycled blend mitigates defect accumulation and porosity growth, ultimately sustaining part quality during long-term recycling.