Microstructure Evolution, Tribological and Corrosion Properties of Amorphous Alloy Strengthening Stainless Steel Fabricated by Selective Laser Melting in NaCl Solution

As a type of austenitic stainless steel, 316L stainless steel has excellent plasticity, corrosion resistance, and biocompatibility, making it widely used in industries, especially in the marine environments. However, its lower yield strength and wear resistance are the obvious disadvantages that restrict its application in more fields. In this work, an Fe-based amorphous alloy (Fe^am) was selected as reinforcement to enhance the 316L stainless steel prepared by selective laser melting (SLM), and microstructure evolution, mechanical properties, tribological and corrosion performance of the SLMed samples were investigated in detail. The relative density values of both 316L stainless steel and Fe^am-reinforced samples are above 99%, which suggests that Fe^am-reinforced samples also have outstanding formability. In the as-etched micrograph, all of the SLMed samples exhibit cellular structure. Fe^am-reinforced samples have thicker sub-grain boundaries, and retained amorphous phase can be observed in the samples reinforced with 10 wt% and 15 wt% Fe^am. As the addition of Fe^am increases, the microhardness and compression strength of the Fe^am-reinforced samples gradually improve and reach 449.2 HV and 2181.9 MPa, respectively. The wear morphologies show that the 316L stainless steel and Fe^am-reinforced samples both experience abrasive wear and corrosion wear in a 3.5 wt% NaCl solution. Meanwhile, as the amount of Fe^am added increases, the coefficient of friction and wear rate of SLMed samples gradually decrease. Compared to the unreinforced sample, Fe^am-reinforced samples have lower corrosion current density and higher pitting potential according to the potentiodynamic polarization curves and also exhibit superior corrosion resistance in the salt spray environment. This work suggests that the addition of Fe-based amorphous alloy can improve the mechanical properties and wear resistance of 316L stainless steel, as well as its ability to withstand salt spray corrosion.