Abstract: Laser cladding improves the performance of metal surfaces and achieves surface strengthening. However, it is often found that due to the reduced toughness of the coating, cracks and defects appear on the surface of the coating. The reasons for cracks in laser clad coatings due to reduced toughness are summarized, including internal stress caused by temperature gradient difference, stress concentration in laser clad layers, and small pores in clad layers. At the same time, factors affecting the toughness of laser clad layers are summarized, including the selection of clad materials, the setting of laser cladding process parameters, and the heat treatment methods of cladding materials. On this basis, the progress in improving the crack defects of laser clad coatings in recent years is emphasized, and methods to enhance the toughness of laser clad coatings are studied and searched for, including adding composite ceramic reinforcement phase and rare earth element powder to the cladding powder to change its composition, adding a transition layer between the substrate and the cladding layer, changing laser cladding process parameters such as the laser power, scanning rate, and spot diameter, preheating the substrate before cladding and heat treating the coating after cladding, external ultrasonic vibration and electromagnetic field, as well as coupling of ultrasonic vibration and electromagnetic field and other energy field assistance. Aiming at the shortcomings of various methods for enhancing the toughness of laser clad coatings, the research prospects of future methods for toughening and modifying laser clad coatings are explored.

Key words: laser cladding, coating toughness, cracks, toughening method