Surface enhancement of laser-cladded coating induced by a hybrid laser method

The surface quality of laser-cladded coatings has been challenged due to their rough surface, which usually requires further post-processing. In this study, a hybrid laser engraving-polishing method has been proposed to enhance both surface quality and mechanical performance of stainless steel coatings. The results demonstrate that the surface roughness of cladding coating was reduced from Sa 22.7 μm to Sa 0.65 μm through sequential laser engraving and polishing processes. The material removal rate was increased with the assistance of oxygen during laser rough engraving. The degree of elemental evaporation was decreased and surface quality was improved by laser finish engraving under the argon shielding. Due to the elemental evaporation of Cr and Mn, α'-martensitic transformation occurred in the remelted layer during laser engraving, and a fully δ-ferrite layer with high density of dislocations formed after laser polishing. Therefore, the microhardness and wear resistance of the final surface were significantly enhanced by the hybrid laser processing.