Numerical and experimental analysis for morphology evolution of 6061 aluminum alloy during nanosecond pulsed laser cleaning

Laser cleaning technology has become an important method for surface cleaning of aluminum alloy oxide film. However, the heat and mass transfer mechanism during the laser cleaning process is still unclear, which hinders the precise control of surface morphology. In this work, a 3D heat transfer and flow coupling model of laser cleaning for aluminum alloy oxide film was established, and the dynamic evolution behavior of surface morphology with different average laser power (PL) was analyzed. The simulation morphology was agree with experimental results. There is no splashing for PL as 20 W, while a large amount of splash is generated as PL increased to 40 and 60 W. The morphology evolution is mainly attributed to the combined effects of recoil pressure, surface tension and gravity. The maximum flow velocity (v) is only 5 m/s for PL as 20 W, while v can reach 150 m/s for PL as 40 and 60 W. With increasing PL, the depth of molten pool reached 4.5, 5 and 8 mu m for 20, 40 and 60 W, respectively. The strong heat effect caused by high PL can not only enhance the melting phenomenon, but also enhance the force effect, which plays an important role in the morphology evolution.