Research on the influence of laser molten pool flow and evaporation on the bump texture forming of aluminum plate surface

Abstract

At present, the research of laser texture mainly focuses on the machining quality and its properties, but the forming mechanism of laser bump texture surfaces is relatively less studied. In this paper, a long pulse laser ablation model was established based on the laser molten pool flow and evaporation phenomena by numerical simulation. And the evolution mechanism of bump texture morphology on metal surface during laser irradiation time was studied. The results show that the bump texture morphology shows edge protrusions and central depressions, and in the cooling stage, under the action of surface tension, the concave and convex height will show a rebound phenomenon. At the same time, the influence of laser parameters on the morphology of laser bump texture was studied by experiments. By comparing the numerical simulation with the experimental results, it can be found that when the laser irradiation time is equal to 0.5 ms, the morphology obtained by numerical simulation is close to the experimental results. In addition, the differences of pressure field and velocity of vaporized metal gas at different time and under different laser power are compared. Finally, the plasma on the surface of aluminum during laser machining captured by a high-speed camera indirectly indicates that the evaporated metal gas ionizes and forms a stable plasma layer floating above the target material.