High temperature tribology and wear of selective laser melted (SLM) 316L stainless steel

Abstract

High temperature wear behaviour of selective laser melted (SLM) 316L stainless steel (SS) was studied to elucidate the influence of characteristic microstructure of SLM 316L SS on the wear properties. The wear tests were conducted from room temperature (RT) to 600 °C using ball-on-disc setup with alumina counter ball. The effect of temperature on the wear rate and the underlying mechanisms were evaluated and compared with conventional 316 SS. The RT coefficient of friction (COF) and wear rate of SLM 316L SS and conventional 316 SS were 0.5 and 4.6 ± 0.4 x 10−4 mm3/Nm and 0.7 and 4.5 ± 0.1 x 10−4 mm3/Nm, respectively. The wear rate of conventional 316 SS slightly decreased with increasing temperature from 4.5 ± 0.1 x 10−4 mm3/Nm at RT to 3.2 ± 0.1 x 10−4 mm3/Nm at 300 °C, followed by increasing to 4.9 ± 0.4 x 10−4 mm3/Nm at 400 °C, while the wear rate of SLM 316L SS was twofold lower with 2.3 ± 0.6 x 10−4 mm3/Nm at 300 °C and 2.7 ± 0.3 x 10−4 mm3/Nm at 400 °C. The wear rate at 600 °C was found to be comparable between SLM 316L SS and conventional 316 SS with a wear rate of 6.4 ± 0.7 x 10−4 mm3/Nm and 6.6 ± 0.6 x 10−4 mm3/Nm, respectively. The lower wear rate in SLM 316L SS at higher temperatures of 300 °C and 400 °C was due to its stable hierarchical microstructure, cellular subgrains, formation of stable oxide glaze and higher hardness. Moreover, the cross-sectional microscopy of wear track after 600 °C wear tests showed that the deformation zone below the wear track in SLM 316L SS was 10–15 μm compared to 30–40 μm for conventional 316 SS. The two folds low wear rate of the SLM 316L SS at 300 °C and 400 °C compared to conventional 316 SS could potentially render it for usage in applications where high temperature wear resistant SS are needed.