Numerical simulation and experimental analysis on nanosecond laser ablation of titanium alloy

Abstract

Nanosecond lasers are widely used in the ablation of metal materials, and the exploration of the ablation mechanism has never stopped. In this study, a three-dimensional finite element model of heat transfer and flow coupling was established with Ti6Al4V alloy as the research object. The model simulated the heat transfer in the ablation process by setting heat conduction, convection, and radiation flux. The surface tension, recoil pressure, gravity, buoyancy, and thermocapillary force were used as driving forces to induce fluid flow in the molten pool. The results show that different scanning paths lead to different degrees of heat accumulation in the model. However, due to the large duty cycle used in the simulation, the model has enough cooling time. The effect of heat accumulation is limited. Among the reasons for inducing liquid flow in the molten pool, thermal capillary flow dominates. The maximum flow velocity appears at the edge of the molten pool, and the flow velocity gradually decreases from the surface to the inside. To study the interaction between laser parameters and groove size, the experimental parameters were designed by response surface methodology. The results show that the influence of scanning times, scanning speed, and repetition frequency on groove depth gradually decreases. The interaction between scanning speed and scanning times has an obvious effect on the groove width.