On the Effect of Small Laser Spot Size on the Mechanical Behaviour of 316 L Stainless Steel Fabricated by L-PBF Additive Manufacturing

This research effort experimentally investigated the influence of small laser spot size (LSS – 50 μm and 100 μm) on the mechanical behaviour of additively manufactured 316L Stainless Steel (SS) samples produced by laser-powder bed fusion on a single metal 3D printer. The effect of main process parameters including scanning speed (1400, 1700 and 2000 mm/min), layer thickness (30, 55, and 80 μm), build direction (0o, 15o and 30o, 90 o or flat) and printing power (100, 200, and 350W) was analysed. Tensile tests together with scanning electron microscopy were carried out to determine the mechanical behaviour and fractography pattern of the parts produced with different parameters. When changing the build direction, the results led to a nearly isotropic mechanical behaviour in combination with the manufacturing equipment. By employing small laser sport size, the melt pool depth was increased, which in turn led to an enhancement in the mechanical performance of the fabricated 316L SS. Printed specimens displayed ultimate tensile strength values of 165–550MPa (LSS of 50μm) and 147–519MPa (LSS of 100μm), yield strengths of 137–402MPa (LSS of 50μm) and 120–385MPa (LSS of 100μm), with an elongation at break of 5–64%.