Abstract
Despite the attractive capabilities of additive manufacturing (AM) technology, the industrialization of these processes remains very low. This is attributed to the complexes physical phenomena involved in the AM process and the layered structure of the produced parts. Intense research work is still needed for the prediction and optimization of AM parts mechanical properties. In this study, the influence of particle size distribution (PSD) of stainless steel 316L (SS 316L) powders on AM parts properties was investigated. Four PSD were used to produce test parts and compare the resulting porosity, surface roughness and macro-hardness. The SS 316L specimens were fabricated by Laser Powder Bed Fusion process (LPBF) on a SLM 125HL machine using variations in laser power and scan velocity. Computed scan tomography (CT) was used to characterize the defects. Lack of fusion and keyhole defects were detected. Defects were detected even in nearly dense parts. The powder size distribution was found to affect the porosity. Results from CT tests were used to identify the minimum achievable porosities for each powder, through the appropriate selection of process parameters. The macro-hardness and surface roughness were found to vary with the powder properties.
Highlights
Additive manufacturing (AM) is a promising technology enabling the fabrication of parts with customizable designs, near-net shape geometries and high mechanical properties using various materials including metallic, ceramic and polymer materials [1,2]
Several studies have confirmed that the particle size distribution (PSD), flowability and morphology of metallic powder material have a major impact on the density of final parts
The surface roughness of the AM samples depends on the chosen processing parameters and the layer coating system
Summary
Additive manufacturing (AM) is a promising technology enabling the fabrication of parts with customizable designs, near-net shape geometries and high mechanical properties using various materials including metallic, ceramic and polymer materials [1,2]. Their study showed that powder mixtures with more and smaller particles can compensate the defects in powder bed and improve parts density. Liu et al [8] investigated the effect of laser and SS 316L powder properties on final AM part performance They obtained higher density parts with smoother side surfaces using powder with wider range of particle size, whereas, the powder with narrower range of particle size provided higher ultimate tensile strength and larger hardness. Balbaa et al [9] studied the influence of AlSi10Mg powder particle size on the LPBF processibility by considering the material physical properties. They used fine (D50=9μm) and coarse (D50=40μm) powders.
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