Effect of Microstructure on Salt Spray Corrosion Resistance of Laser Clad Layers

Three different laser clad layers were fabricated from H13 steel, Ni55 and WC powders onto the surface of 4Cr5MoSiV1 steel using high power diode laser (HPDL) cladding so as to improve the salt spray corrosion resistance of the steel. By means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS) as well as the salt spray corrosion testers, the morphology, microstructure as well as corrosion properties of the clad layers were analysed. The microstructure affects greatly the salt spray corrosion resistance of laser clad layers. The nanoscale carbide particles along grain boundaries of laser clad layer deriving from the reaction between H13 powder and WC particles, reduce the penetration access of Cl- ion and thus prevent the permeation of corrosion medium into the H13+20%WC clad layers. The salt spray corrosion resistance of H13+20%WC clad layers is better than that of the H13 clad layer and Ni55+20%WC clad layer.