Effect of different laser wavelengths on laser cladding of pure copper

The blue laser provides a fresh direction for the laser cladding of pure copper materials which have high reflectivity to the infrared laser. Herein, the laser cladding of pure copper is carried out on 316 stainless steel substrates using blue laser and infrared laser. Specifically, the cladding spatters, macroscopic morphology, microstructure, and microhardness were studied by comparing the cladding under these two lasers. The laser absorption of copper does not change sharply with temperature and is higher under blue laser, which is proved to be more conducive to the stability of the molten pool during the cladding process and enables the preparation of coatings with fewer defects at lower energy densities. Also, it is found that the average hardness of the coatings prepared under an infrared laser (166.2 HV0.1) is higher than that prepared under a blue laser (133 HV0.1). This is because the keyhole tendency under an infrared laser enhances the Marangoni convection and leads to a more pronounced diffusion between elements and more Fe-rich phases in the coatings. Overall, this work deepens the understanding of pure copper materials cladding at different-wavelength lasers and provides a reference for blue laser cladding on highly reflective materials.