Microstructure and mechanical properties of parts produced by laser powder bed fusion of AlSi10Mg powder with coarse particle size

Powder size and morphology play a central role in laser powder bed fusion of metallic components, influencing the process stability, microstructure, and mechanical properties. In the pursuit of more efficient production, coarse powders (~90 μm and greater) have become commercially available, enabling increased layer thickness and build rate. For AlSi10Mg, only limited data exist on how such coarse powders perform during additive manufacturing in medium-wattage (400 W) systems and on what microstructures and mechanical properties can be achieved in parts 3D-printed using these powders. The present study addresses this gap by characterizing parts produced using NExP-1 AlSi10Mg, a novel non-combustible and non-explosible powder with uniform spherical morphology and a median size of ~90 μm. The microstructure and tensile properties have been assessed in samples manufactured using three distinct combinations of process parameters, resulting in relative densities of 97.5–99.6 % (measured using Archimedes' principle). Results obtained in this study show that an increased hatch distance at a low scan speed significantly reduces the relative density due to lack-of-fusion porosity, which leads to decreased strength and ductility compared to those in a sample with the highest density. The pore population characterized using micro-computed tomography is found to be related to sample density: the highest-density sample primarily contains isolated pores, whereas lower-density samples display higher frequences of interconnected pores. This work provides new insights into the potential of coarse AlSi10Mg powders and serves as the basis for further process optimization for demanding industrial applications. • Non-explosive coarse AlSi10Mg powder was evaluated for medium-wattage LPB-LB. • High relative density (99.6 %) was achieved for optimized printing parameters. • Micro-CT revealed the predominance of blade-like pores and plate-like pores. • Fine cells (~0.5 μm) within melt pools indicate rapid solidification. • Mechanical strength was similar to or higher than those for parts from finer powder.