Relationship Between Grain Size and Corrosion Resistance of (Ti-V)Cp/Fe Composite Laser Clad Layers
H. Zhang, S-T. Jiang, K-T. Mei, Y-Q. Duan and X-J. Cha
Few reports are focused on the relationship between corrosion resistance and grain size of second phase reinforced metal matrix composite (MMC) materials. This study successfully prepared a submicron ultrafine grained (Ti-V)C/Fe composite layer by simultaneously regulating the laser cladding process parameters and the alloy powder particle size. The regression relationship between the layer’s corrosion current density, Icorr, percentage of (Ti-V)C, PC, and grain size of carbides, dC and layer’s matrix, dFe was established, that is Icorr=22.53+1708.47PCdC–76.92dFe μA/cm2. As the average grain size of Ti-V carbides increases or the Febased layer matrix decreases, the corrosion current density of the composite layer increases and vice versa. The results of immersion tests confirmed that the smaller the (Ti-V)C particles, the better the corrosion resistance of layers. Also, the smaller the layer matrix grains, the more the preferential corrosion at the grain boundary, more favourably forming a corrosion product film.
Keywords: Fibre laser, carbides, Fe-based powder, metal matrix composite (MMC), laser cladding, grain size, corrosion resistance