Effect of ultrasonic vibration power on the microstructure and properties of laser cladding in-situ NbC/WCoB coatings

In-situ NbC/WCoB composite coatings were fabricated on AISI 1045 steel substrate using ultrasonic vibration-assisted laser cladding. This study systematically investigated the effect of varying ultrasonic vibration power on the phase composition, microstructure, microhardness, fracture toughness, fracture morphology, and wear resistance of coatings. The results indicate that while ultrasonic vibration did not significantly alter the phase composition, it played a crucial role in microstructural refinement. A fine microstructure was obtained at an ultrasonic vibration power of 750 W, which also facilitated a strong metallurgical bond between the coating and the substrate. Consequently, the coating prepared at 750 W exhibited optimal mechanical and tribological properties, including a microhardness of 1862.5 HV 0.5 , a fracture toughness of 8.65 MPa‧m 1/2 , and a wear resistance of 4.65 × 10 −5 mm 3 /Nm. Furthermore, ultrasonic vibration reduced microhardness fluctuation of the coating. Fracture analysis revealed a predominantly transgranular cleavage mechanism, with some intergranular cracking. These findings demonstrate that applying an appropriate level of ultrasonic vibration power is an effective strategy for significantly enhancing the performance of in-situ NbC/WCoB composite coatings. • In-situ NbC/WCoB coatings made via ultrasonic vibration-assisted laser cladding. • Ultrasonic vibration refines microstructure and improves elemental homogeneity. • Ultrasonic vibration enhances wear resistance and fracture toughness. • Fine microstructure at 750 W leads to strong metallurgical bonding. • Coating hardness reaches 1862.5 HV 0.5 at optimal ultrasonic vibration power.