Fabrication and characterization of self-lubricating anti-wear 316L stainless steel/h-BN composite coatings on Q235 substrate via laser cladding

Abstract

This paper presents the fabrication and characterization of self-lubricating, anti-wear 316L stainless steel composite coatings on a Q235 substrate using 316L stainless steel powders and nanoscale hexagonal boron nitride (h-BN) ceramic particles via coaxial powder feeding laser cladding. The influence of process parameters on cladding quality and geometry, and the impact of h-BN contents (2 wt% and 5 wt%) on the microstructure and mechanical properties of the coatings were studied. Optimal process parameters for 316L/5wt%BN coatings were identified: a powder feeding rate of 3–4 rpm, a laser power of 2200–2400 W, a scanning speed of 4–5 mm/s, and an overlapping rate of 40 %. Microstructural analysis showed a smooth surface without cracks or pores. X-ray diffraction revealed intermetallic compounds such as CrB, Cr2N, Fe3N, BN, and γ-(Fe, Ni). The inclusion of h-BN nanoparticles enhanced grain refinement, significantly increasing microhardness. Coatings with 5 wt% h-BN achieved an average microhardness of 438.8 HV10, 2.5 times higher than the substrate and the 316L stainless steel. Additionally, h-BN reduced friction coefficients, leading to substantial wear reduction. The 316L/5 wt% h-BN sample experienced only 4.2 mg of wear, 45.16 % of the substrate’s wear. These findings highlight the beneficial effects of h-BN nanoparticles on 316L stainless steel coatings, enhancing wear resistance, hardness, and overall performance.