Laser Cladding Crack Detection: Acoustic Signal Analysis for Defect Identification

Cracks are one of the most significant defects affecting the quality of the cladding layer [11]. Due to the rapid heating and cooling process of laser cladding, the cladding powder and substrate quickly melt and solidify, resulting in various internal stresses in the cladding layer and the formation of cracks [9,12-14]. During the laser cladding process, there are many reasons for crack formation, but it is mainly related to the significant residual stresses within the material during the laser cladding treatment. These stresses can be attributed to thermal stress and phase transformation stress [15-18]. When the residual stress within the cladding layer exceeds the yield strength limit of the material, cracks will occur and quickly release energy, resulting in the generation of transient elastic waves and sound [19,20]. Therefore, by collecting the acoustic signals of cladding cracks and conducting processing and analysis, it is possible to achieve the detection and identification of laser cladding layer crack defects [21].