Effect of Laser Power on the Electrochemical Performance of a Ni-60%WC Alloy Laser Clad Coating on H13 Steel
Y. Ge, C-Y. Zheng, L-J. Dai, C. Liu and D-J. Kong
Ni-60%WC alloy coatings were prepared on the surface of a H13 steel substrate by laser cladding with a fibre laser at different laser powers. The microstructure and phases of the laser clad Ni-60%WC alloy coatings fabricated with laser power of 2100, 2500 and 2900 W were analyzed, and the electrochemical performance was measured by the potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS). The results showed that the laser clad Ni-60%WC alloy coatings were composed of WC, W2C, and NiC phases, and the WC particles were homogeneously distributed throughout the coating cross-sections to form sound metallurgical bonding with the H13 steel substrate. The corrosion current density icorr, and polarization resistance Rp, were lowest on the laser clad Ni-60%WC alloy coating fabricated with a laser power of 2500 W. The impedance of this sample also exhibited the largest, demonstrating that the appropriate laser power will improve corrosion resistance.
Keywords: Fibre laser, H13 steel, Ni-60%WC alloy, laser cladding, laser power, microstructure, phase, electrochemical corrosion