Wear anisotropy of selective laser melted 316L stainless steel

Selective laser melting (SLM) is one type of metal additive manufacturing technology. Large thermal gradient during SLM process leads to differences in microstructures and further influences mechanical properties, resulting in anisotropy. However, the influence of the anisotropic microstructures on the wear behavior has not been studied. This is crucial for fabricating a wear resistant surface using SLM. In this paper, 316L stainless steel samples were produced using SLM and the microstructures of three different surfaces were characterized. The wear behaviors on different surfaces along six scratching directions including F-x, F-z, S-y, S-z, T-x and T-y were studied by performing single and multiple passes scratch tests. The results indicate that the top surface is mainly composed of cellular structures while the side surface is characterized by columnar structures. Both columnar and cellular structures are found in the front surface. Under the load of 1 N, significant difference in scratch depths was found between S-y and S-z. The main failure mechanism is found to be due to slipping. Both highest and lowest wear appear on the side surface in two sliding directions: S-y exhibits the highest wear resistance while S-z shows the lowest wear resistance. Under 3 N, the difference between different sliding directions is less pronounced with the fracture of cellular structure while S-y still shows the lowest scratch depth. Under 5 N, similar wear behavior in terms of cracking were found in all scratch grooves.