Study on the morphology of oxide layer on aluminum alloy cleaned by nanosecond laser

As a common alloy material, aluminum alloy has a good application prospect in the fields of construction, automobile, electric power and aerospace.There is a layer of high melting point oxide film on the surface of aluminum alloy, which will hinder the laser energy transfer, lead to poor welding stability, and easily lead to welding defects such as porosity and inclusion in the weld; the surface of aluminum alloy has high reflectivity of laser, which makes the utilization rate of laser energy low, which is easy to cause welding defects such as incomplete penetration and incomplete fusion. Therefore, the surface of aluminum alloy should be pretreated before laser welding. Laser cleaning is an advanced and environmentally friendly cleaning technology. A Nd: YAG laser with 1064 ns pulse width was used to study the morphology of aluminum alloy under the action of nanosecond laser pulse cleaning.The laser-treated surfaces were characterised using metallurgical microscope. Successful oxide removabove certain thresholds that defined the lower end of the process operating window for pulse operation . The ablationechanisms involved in the removaloxide firom 1064nm and found to combineboth thermal and mechanical effects , the surface melting first occurring at fluences lower than those at which cleaning is initialised.In the process of laser cleaning, new oxide layer is formed.