Wear anisotropy of selective laser melted 316L stainless steel

Influence of laser post-processing on pore evolution of Ti–6Al–4V alloy by laser powder bed fusion

The rapid development of three-dimensional (3D) printing technology opens great opportunities for the design of various multiscale lubrication structures. 3D printing allows high customization of a...

Infinite Approaching Superlubricity by Three-Dimensional Printed Structures.

The effects of process parameters on microstructure and mechanical properties of the 316L stainless steel helical micro-diameter spring (316L HMDS) fabricated by selective laser melting (SLM) were explored. By optimizing SLM process parameters, the near-full density (> 99%) SLM-316L HMDS can be manufactured. The SLM-316L HMDS exhibits typical layered morphology consisting of micron-sized melt pools and columnar grains whose growth orientations are consistent with the temperature gradient. Lower hatch space reduces the formation of voids, resulting in better density, elongation, and ultimate tensile strength of the SLM-316L HMDS. The form angle significantly affects the yield strength and ultimate tensile strength, and obvious dimples appear on the fracture surface, demonstrating toughness fracture. The experimental results establish the correlation between the process parameters of SLM and the microstructure and macro-mechanical properties of the SLM-316L HMDS.

Effect of selective laser melting process parameters on microstructure and mechanical properties of 316L stainless steel helical micro-diameter spring

Additive manufacturing of metallic tribological components offers unprecedented degrees of freedom, but the surface roughness of most as-printed surfaces impedes the direct applicability of such structures, and postprocessing is necessary. Here, the tribological performance of AISI H13 steel samples was studied. These were additively manufactured through laser powder bed fusion (L-PBF), also referred to as selective laser melting (SLM). Samples were tested in four different surface conditions: as-printed, polished, ground and polished, and laser-surface-textured (LST) with round dimples. Friction experiments were conducted in a pin-on-disk fashion against bearing steel disks under lubrication with an additive-free mineral base oil for sliding speeds between 20 and 170 mm/s. Results demonstrated that, among the four surface treatments, grinding and polishing resulted in the lowest friction coefficient, followed by the as-printed state, while both polishing alone and laser-surface texturing increased the friction coefficient. Surprisingly, direct correlation between surface roughness and friction coefficient, i.e., the rougher the surface was, the higher the friction force, was not observed. Wear was minimal in all cases and below what could be detected by gravimetrical means. These results highlight the need for an adequate post-processing treatment of additively manufactured parts that are to be employed in tribological systems.

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Guoliang Lin

Papers

Material characterization and lubricating behaviors of porous stainless steel fabricated by selective laser melting