Laser cladding with continuous Ni-Al bronze wire feeding for repairing marine components

Abstract

Laser cladding of a Ni-Al bronze layer on a bronze substrate has been investigated for repairing marine components. The laser cladding was conducted using a 3 kW cw CO2 laser with simultaneous feeding of the Ni-Al bronze wire into the molten pool. The geometry and microstructure of the laser-clad layer depend on laser processing parameters. With optimized processing parameters, a relatively uniform and smooth clad layer is obtained. The microstructure of the laser-clad layer was studied with optical microscope and X-ray diffraction (XRD) techniques. The hardness of the clad layer is substantially higher than that of the substrate bronze. However, the hardness in the clad layer is significantly affected by the laser heat input as well as the substrate cooling effect. Experimental results show that the hardness in the laser-clad layer reduces with the increased heat input. Tensile residual stresses on the surface of the laser-clad layer were determined by using an XRD method. Electrochemical polarization testing in a 3.5% NaCl solution shows that the corrosion resistance of the laser-clad layer is similar to that of substrate bronze.