Study on the blowing-assisted laser ablation characteristics and numerical simulation of titanium alloys

Titanium alloys are widely used in aerospace, automobile manufacturing and biomedical fields due to their excellent comprehensive performance. TC4 titanium alloy is a typical difficult-to-machine material due to its poor machinability and machining difficulty. During conventional laser processing of titanium alloys, the oxides generated in the machining area will affect the material removal effect. How to avoid the buildup of oxides is a key issue in the processing of TC4 titanium alloy. This paper investigated the effect of blowing assistance on the laser ablation characteristics of TC4 titanium alloy, and carried out the blowing assistance laser ablation tests. And the laser ablation threshold of TC4 titanium alloy was calculated using the equivalent diameter method. The effect of laser power and blowing assistance on the surface roughness of the edge of the ablated holes and the depth of the holes were explored. The results show that when the repetition frequency is 10kHz, the wavelength is 532nm, and the ablation time is 6s, the laser ablation threshold of TC4 titanium alloy is calculated to be 0.363J/cm², and the surface roughness and hole depth of the ablation hole edges increase with the increase of the laser power or the application of the blowing assistance. Combined with the characteristics of heat transfer and material vaporization in laser ablation, the pulsed laser could be equivalent to a continuous laser, on the basis of which a two-dimensional transient numerical model was established, and the evolution of the surface topography of the workpiece in laser ablation is simulated to predict the trend of the hole depth under different powers. The results show that the average error between the simulation and the experimental results under the three laser powers is 11%. The research work in this paper can provide a reference for the optimization of laser machining process parameters of TC4 titanium alloy.