Amorphous/nanocrystalline coating on 45 steel prepared by laser processing of pre-electrodeposited coating

In this study, a composite electroplating method was used to improve the traditional feeding processes in laser cladding. First, 45 steel was pre-coated with a mixture of Fe-based amorphous powders and Co via electrodeposition. Then, laser cladding was carried out to obtain an amorphous–nanocrystalline coating. The morphology, hardness, wear resistance, and corrosion resistance of the coating were characterized, and the phase evolution was studied. Benefiting from the superior glass forming ability and fast solidification, amorphous phase and nanocrystals were formed in the coating. The coating was predominantly made up of CoFe and Fe3Co crystalline phases, with a minor quantity of complex amorphous phases. The amorphous–nanocrystalline coating demonstrated exceptional surface properties. It had a notable hardness of 10.88 ± 0.32 GPa, which was higher than that of 45 steel by 4.3 times. Its wear rate, corrosion current density (Icorr), and polarization resistance were 0.343 ± 0.037 (37.5 % lower than that of 45 steel) and 1.385 ± 0.193 μA⋅cm−2 (1/8 times that of the matrix), and 13,992.92 ± 1165.9 Ω⋅cm2 (nine times that of 45 steel), respectively.