On enhancing surface wear resistance via rotating grains during selective laser melting

Selective laser melting (SLM) enables fast and reliable fabrication of metallic parts. Yet post-processing techniques are still required to achieve desirable surface properties, such as wear resistance, surface quality, before the components are ready for deployment in the field. Given the complexities associated with post-processing, alternative approaches are needed. To this end, tailoring process parameters during SLM could be an efficient way to increase wear resistance. However, the relationship between process parameters, micro-structure, and wear mechanism must be clarified first. In this study, three scanning strategies are applied to tailor the microstructure of SLM fabricated 316 L stainless steel samples. They are: without remelting (zigzag), remelting with a 0 degrees (zigzag-R0), and 90 degrees (zigzag-R90) rotation and different hatch spacings. The effects of grain orientation on wear resistance are studied by performing scratch tests. It is shown that remelting with small hatch spacings results in the transition of crystallographic texture from the single fiber <001> texture to cubic textures, causing the remelted samples to have high wear resistance through aligning the grains orientations to resist slip. The intensity of textures tends to increase with decreasing the hatch spacings. The maximum enhancement of wear resistance is found in the zigzag-R90 samples using a hatch spacing of 10 mu m, leading to 90.8 % and 96.7 % reductions in scratch depth and wear rate, respectively. Such a method can be used in increasing surface wear resistance of SLM fabricated components.