Research status and development trends of heat treatment on defect inhibition in cladding coatings

Laser cladding technology, as an advanced surface strengthening and repair technique, has been widely applied in aerospace, mechanical manufacturing, mining, and other fields. However, the rapid heating and cooling thermal characteristics during the cladding process can easily lead to defects such as cracks, pores, residual stresses, and compositional segregation in the coating, severely affecting its forming quality and service life. Heat treatment, as a key method for regulating the microstructure and properties of cladding coatings, including preheating of the substrate before cladding and post-cladding heat treatment processes, can effectively inhibit defect formation, optimize microstructure, and enhance overall performance. In this review, the efficacy of substrate preheating and post-cladding heat treatment in defect management was systematically examined. The inherent technical characteristics of these heat treatment modalities and their corresponding roles in defect mitigation were analyzed. Furthermore, future developmental trajectories of heat treatment technologies aimed at defect suppression in cladded coatings were projected, thereby furnishing a theoretical foundation and technical guidance for the fabrication and application of high-performance cladded coatings.