Effect of TiC mass fraction on the microstructure, microhardness, and corrosion resistance of TiC/Fe composite coatings

TiC/Fe cladding layers with different mass fractions of TiC were deposited on the surface of 45 steel by laser cladding technology, and their microstructure, microhardness, and corrosion resistance were investigated. Results show that the dendrites of the Fe35-fused cladding are composed of α-Fe solid solution, which is rich in Fe, Cr, Si, Mn, and Ni elements; the intercrystal is a cocrystal composed of α-Fe solid solution and (Cr, Fe)7C3, which is rich in Cr and C elements; the fused cladding is composed of columnar crystals, columnar dendrite crystals, and equiaxed crystals in the order from the bottom layer to the upper layer. In the 10% TiC-fused cladding, the bottom layer consists of columnar crystals, while the middle and upper layers are composed of equiaxed crystals. TiC is dispersed as fine, diffused small particles and small pieces within the matrix. Conversely, the fused cladding layers containing 20% and 30% TiC comprise equiaxed crystals, with TiC distributed in the matrix as agglomerated large particles and pieces. With an increase in TiC content, the bonding of TiC to the surrounding matrix diminishes. The 10% TiC-fused cladding exhibits the highest average microhardness, whereas the 20% TiC-fused cladding demonstrates the lowest average microhardness. The fused cladding without TiC addition displays the most positive corrosion potential, the lowest corrosion current density, the most stable passive film, and the best corrosion resistance. The corrosion resistance of the fused cladding diminishes following the addition of TiC; the higher the TiC content, the poorer the corrosion resistance of the fused cladding.