Effect of laser remelting and ultrasonic irradiation on crack suppression and properties of Ni-WC laser cladding layer

This study investigates crack suppression mechanisms in Ni60-WC laser cladding layers on C45E4 steel using ultrasonic irradiation and laser remelting. C45E4 steel, widely used in industrial gears and shafts, suffers from wear and corrosion in heavy-load environments. Laser cladding provides surface reinforcement, but cracks persist due to thermal stress and WC/matrix mismatch. Key findings reveal that ultrasonic cavitation breaks dendrites through micro-jet impacts, while acoustic streaming homogenizes the melt pool, reducing elemental segregation. Laser remelting eliminates cracks by remelting defect-prone regions (e.g., interfacial porosity) and releasing residual stress through thermal equilibrium. ​​The experimental findings demonstrated that ultrasonic waves significantly enhanced the crystal strengthening effect of the fused cladding, resulting in a 17.54% increase in hardness.​​ Furthermore, the combined laser remelting and ultrasonic-assisted process effectively prevented crack formation in the cladding layer and enhanced the hardness of the substrate. Despite partial WC dissolution, ​​hardness improvements remain significant​​ due to grain refinement. This dual-assisted strategy demonstrates practical value for repairing C45E4 components in mining and energy equipment.