Effect of multiple laser shock peening on the microstructure and properties of laser cladding nano-WC/Ni60 composite coatings

Laser cladding (LC) is an effective method for repairing damaged parts, but LC coatings often have problems such as residual tensile stress and coarse grain size. In this paper, we improve the microstructure and properties of the composite coatings by LC WC/Ni60 on the impeller surface, followed by multiple laser shock peening (LSP) treatments. Meanwhile, the effects of multiple LSP on the microstructure, microhardness, residual stress, wear resistance and corrosion resistance of the composite coatings were systematically investigated. The LSP induced plastic deformation, introducing beneficial residual compressive stresses and refining the microstructure, which effectively improving the wear resistance and corrosion resistance of the composite coating. The average grain size of the composite coating was reduced by 12.9 % after three times LSP, all residual tensile stresses were transformed into residual compressive stresses, the wear rate was reduced by 27.5 % and the self-corrosion current density was reduced by 77.1 %.