Effect of Heat Treatment and Anisotropy on Microstructure and Wear Resistance of 316L Stainless Steel Prepared via Selective Laser Melting

316L stainless steel was prepared via selective laser melting (SLM), and the effect of heat treatment on microstructure, density, microhardness and wear resistance were studied. The results show that specimens exhibit anisotropy in microstructure, density, microhardness and wear resistance, the microhardness and wear resistance of XOY plane is higher and better than XOZ plane. X-Ray diffraction (XRD) analysis indicated that specimens exhibit FCC austenite phase, no new phase is found after heat treated, indicating that it has good thermal stability. Microstructure of SLM 316L exhibits obvious melt pools composed of columnar crystals and cellular crystals, some nano silicon oxides adhere to the surface of the cellular crystals. SLM 316L presents as intersecting melt pools on the XOY plane and fish-scale-like melt pools on the XOZ plane. After heat treated, the melt boundaries annihilate and recrystallization of the specimens lead to the coarsening of the microstructure. Microhardness results show the microhardness decrease after heat treated and the specimen with the lowest decrease in microhardness after solution+aging treatment. The friction and wear tests results reveal the specimen after solution+aging treatment has the lowest friction coefficient and smallest wear loss, exhibiting the best wear resistance.