Laser-energy-density-dependent anisotropic tribological behaviour of 18Ni300 steel fabricated by selective laser melting

Laser powder-bed fusion has become one of the most popular additive-manufacturing (AM) techniques for producing complex-shaped, metal engineering parts. However, to fully harness the advantages of AM for engineering steels, a deeper understanding and precise control over how the processing parameters influence the structure and properties of manufactured components are crucial. At present they remain insufficiently well explored. In this study, we systematically investigated the tribological performance of 18Ni300 steel fabricated via selective laser melting (SLM) with three distinct energy densities of the laser. The wear behaviour was evaluated on both the top (XY-plane) and side surfaces (XZ-planes) relative to the build direction to assess the degree of anisotropy. The porosity increased to 22% with a decreasing energy density, with fully dense specimens being achieved at the highest energy density. The energy density influenced the dendrite morphology, with predominantly circular dendrites observed on the top surfaces and columnar dendrites on the side surfaces. Tribological tests were conducted at three contact pressures using a reciprocating ball-on-plate setup (100Cr6 counter ball). Optimal wear performance occurred when sliding perpendicular to the melt-pool boundaries and dendrites. Our results, which link energy density to microstructural evolution and wear mechanisms, demonstrate that strategic print orientation can reduce energy consumption by 300% without compromising tribological performance—enabling more sustainable and cost-effective process optimization. • Higher energy density in printed parts creates larger melt pools and a coarser, reoriented microstructure. • Wear depends on sliding direction and surface in printed parts. • Side surfaces exhibit the best wear performance when sliding perpendicular to the build direction. • Under optimal sliding conditions, energy savings can be 300 %, while maintaining or improving wear performance.