Study of powder recycling and its effect on printed parts during laser powder-bed fusion of 17-4 PH stainless steel

The freedom of design and ability to print complex parts have made laser powder-bed fusion (LPBF) additive manufacturing (AM) a suitable alternative to traditional metal manufacturing approaches. As the focus of metal AM is shifting from prototyping to large-scale production, cutting the cost of AM powder remains a major priority. The metal LPBF process is likely to be more economical if feedstock powders are reusable without sacrificing the physical and mechanical properties of final parts. This work introduces the use of dosage to study powder recycling without adding any virgin powder to the feeder. To understand the effects of powder recycling in LPBF of 17-4 PH stainless steel powders, this work studies the properties of both recycled powders and the printed parts after ten successive prints. Powder rheology, morphology, microstructure, and chemical compositions are investigated to study the effect of recycling. Compared to virgin powder, the average particle size increased slightly while powder flowability decreased significantly in the recycled powders. The effect of powder recycling on the microstructure, chemical composition, porosity, roughness and tensile properties of printed parts are also investigated. Compared to the Print 1, samples printed in the Print 10 showed an increase in pore size (54 %) and surface roughness at the Top surface (17 %) resulting in a ∼7 % reduction in ductility.