Cavitation erosion of laser-clad stellite coating on SLM316L steel

• Surface of SLM316L steel was strengthened using laser cladding technology. • Optimal laser parameters are a scanning speed of 10 mm/s and a power of 1800 W. • Optimal γ/ε-Co ratio enhances cladding stellite layer’s cavitation erosion resistance. • Stellite 12 coating exhibits superior cavitation erosion resistance to Stellite 21 coating. The surface of selective laser melting 316 L (SLM316L) steel was strengthened using laser cladding technology. To investigate cavitation erosion of laser-clad stellite coating on SLM316L steel, a series of tests, including microstructural characterization, hardness, electrochemical behavior and ultrasonic cavitation, were carried out on both untreated and surface-strengthened samples. Specifically, an X-ray diffractometer, a digital microhardness tester, and a scanning electron microscopy were employed to analyze the phase composition, microhardness, microstructure, and surface micromorphology of the materials. The research results indicate that the optimal process parameters for preparing Stellite coatings are a laser scanning speed of 10 mm/s and a laser power of 1800 W. This parameter combination enables the formation of an optimal content ratio between γ-Co and ε-Co phases, thereby significantly improving the strength, hardness, and cavitation erosion resistance of the cladding layer. Compared with Stellite 21 coatings, Stellite 12 coatings exhibit higher hardness and wear resistance, and this advantage stems from the increase in their carbide content. It is concluded that Stellite 12 coating exhibits superior cavitation erosion resistance to Stellite 21 coating under ultrasonic cavitation conditions. This enhanced performance is attributed to the balanced regulation of phase transformation synergy between γ-Co and ε-Co, efficient reinforcement of carbide phases, and the synergistic effect of grain refinement.