Laser Powder Bed Fusion of Stainless Steel 316L for Rectangular Micropillar Array with High Geometrical Accuracy and Hardness.

This study investigates the manufacturability of laser powder bed fusion (LPBF) for fabricating SS316L powder into components with rectangular micropillar arrays on their surface. The rectangular micropillars with different width sizes from 200 to 800 μm were fabricated with various LPBF volumetric laser energy densities and building directions. Scanning Electron Microscope, Optical Microscope, and Vickers hardness test were used to observe the effect of micropillar sizes, the volumetric laser energy densities, and build directions on the morphologies, structural densification, geometrical accuracies, and hardness properties of the fabricated micropillars. In this work, the experimental results present that the optimum volumetric laser energy density to fabricate rectangular micropillars with a minor defect was 105 J/mm. The micropillars fabricated with built direction on 0° and 45° planes had stable morphologies and geometrical accuracies. The fabricated micropillar had larger width and pitch, but smaller gap sizes than their computer aided design designs. The hardness property of fabricated micropillars was affected by the size of micropillars, volumetric laser energy density, and build directions during the LPBF process. In conclusion, the rectangular micropillars with width sizes of 200-800 μm were successfully fabricated on the component's surface created at 0° and 45° planes by LPBF technique using 105 J/mm volumetric laser energy density.