Numerical And Experimental Study On Femtosecond Laser Ablation Of Titanium Alloy

Femtosecond laser has the advantages of high peak power,low thermal damage,high processing precision and precise control.It can be widely used in the fields of micro-nanostructures,micro-joining,perforation and polishing of materials.Since femtosecond lasers are often used for precision machining in small areas,it is difficult to directly detect the temperature of materials using instruments in a short period of time.Therefore,it is necessary to develop a numerical model that can accurately simulate the temperature of materials.At present,most studies use two temperature equation(TTM)to establish a temperature model to calculate electron and lattice temperature changes.Two temperature models are widely used in femtosecond laser processing of metallic materials such as copper,aluminum,and nickel.Titanium alloys have high strength and wear resistance and are widely used in aerospace,aerospace and medical fields.However,titanium alloys are difficult to perform precision machining by conventional methods.Femtosecond laser has great advantages and application prospects in the field of precision machining of titanium alloy.This paper mainly studies the temperature field of femtosecond laser ablation Ti6Al4 V and the influence of different laser parameters on the ablation aperture.The physical process of the interaction between the femtosecond laser and the titanium alloy is analyzed in detail.A numerical model was established based on the two temperature equation,and a femtosecond laser body heat source was used to simulate the femtosecond laser ablation of the titanium alloy.The ablation threshold of femtosecond laser ablation titanium alloy is calculated to be 0.1978 J/cm2.The depth of the heat affected zone of the titanium alloy processed by femtosecond laser is nanometer.The pulse energy density determines the electron lattice equilibrium temperature and coupling time.Reducing the pulse interval time can effectively improve the processing efficiency.The study provides a theoretical basis for femtosecond laser single-pulse ablation of titanium alloys.A heat transfer equation was used to replace two temperature equation to establish a multi-pulse femtosecond laser ablation titanium alloy heat accumulation model.The effect of processing parameters on the macroscopic temperature field of titanium alloy surface was studied under the influence of multiple pulses.Analysis of the heat accumulation temperature may cause oxidation of the ablated surface of titanium alloy.The validity of the model was verified by comparison with the metallographic structure obtained by femtosecond laser processing of titanium alloy.The study provides a theoretical basis for the prediction of macroscopic temperature fields in femtosecond laser multi-pulse processing of titanium alloys.On the basis of numerical calculation,ablation aperture experiment was carried out on titanium alloy plate by femtosecond laser.The area of the resulting micropores was calculated by measuring the pore size.The ablation threshold of femtosecond lasermulti-pulse ablation titanium alloy was obtained by area regression method,and the relationship between the number of pulses and the ablation threshold was obtained.By analyzing the morphology of the ablation holes,the effects of different laser processing parameters on the morphology of the ablation holes are obtained,which provides data guidance for femtosecond laser processing micro-holes.