Effect of laser scanning speeds on the microstructure and corrosion resistance of laser cladding layers

Ni-based alloy coating was prepared on the Q235 steel by thermal spraying and laser remelting process at different scanning speeds,in order to study the effect of laser scanning speeds on the microstructure and corrosion resistance of laser cladding layers.The surface macro-morphology and microstructure were observed with an optical microscope(OM)and a scanning electronic microscope(SEM),and the micro-hardness and corrosion resistance were measured and analyzed with the hardness tester and electrochemical corrosion method.The results show that the microstructure becomes dense and even and the grains become tiny,while the amount of the white-bright dendrites increase and the eutectic compounds between the dendrites reduce with laser scanning speeds increasing.In addition,the micro-hardness and corrosion resistance greatly increase due to grain refinement and so on.As a result,the optimum technological parameters are 3kW in laser power,6mm/s in laser scanning speed and 3mm in beam diameter for the Ni-based alloy cladding layer preparation.The result is expected to provide practical value for selecting reasonable laser cladding technological parameters to achieve optimal performance of the cladding layer.