Characteristics and Electrochemical Corrosion Behaviour of a Ni-Based Alloy Coating on Carbon Steel Formed by Laser-Induction Hybrid Cladding
S-H. Lu and X. Ling
A Ni-based alloy coating was fabricated on the surface of Q345 low carbon steel by CO2 laser-induction hybrid cladding to improve its surface properties. The physical-mechanical behaviour of the Ni-based alloy coating was investigated in terms of microhardness, nanoindentation, and scratch experiments. The corrosion resistance of the Ni-based alloy coating in acidic solutions was evaluated by electrochemical tests. The results showed that the microstructure of the interface region between the Ni-based alloy coating and the Q345 substrate is composed of cellular, columnar, and plane crystals. The main phases of the Ni-based alloy coating included γ-Ni, FeNi3, Cr23C6, and B(Fe, Si)3. In the interface region of the coating, the distribution of the microhardness matched the distribution of alloy elements. Nanohardness in the surface and interface regions of the coating were obtained by nanoindentation tests. The elastic-plastic behaviour of the coating was described by a material constitutive equation. No cracks and material loss were observed in the interface region of the Ni-based alloy cladding coating under dynamic load. The good corrosion resistance of the Ni-based alloy coating in acidic environments can be attributed to the presence of a hard phase and ultrafine microstructure.
Keywords: CO2 laser, Q345 carbon steel, Ni-based alloy, powder, laser-induction hybrid cladding, coating, interface, nanoindentation, microhardness, corrosion resistance