Simulation And Experimental Study Of Picosecond Laser Ablation Of 304 Stainless Steel Based On COMSOL

Picosecond laser could process various materials with high efficiency and good quality due to the superior characteristics of picosecond laser like high repetition frequency,high peak power,extremely short action time and nonlinear absorption,etc.Picosecond laser ablation of materials is a complex process,and this technology could be more useful by investigating the ablation mechanism.However,the picosecond laser ablation mechanism is still incomplete.Hence,it is of great significance to carry out systematic simulation,experimental and theoretically study of the picosecond laser ablation process.The improvement of processing quality and efficiency based on current technology is also worth our in-depth exploration.In this paper,COMSOL was used to simulate picosecond laser ablation of stainless steel,which is widely used in the industry.Subsequently,the corresponding experiments were performed to verify the developed model.The main content of the paper includes the following aspects:1.The dynamic thermo-physical process of picosecond laser ablation of stainless steel target was analyzed.According to actual requirements,a two-dimensional axisymmetric model was established in COMSOL.Thermo-physical parameters related to stainless steel temperature were discussed and used to solve the model.The phase explosion mechanism of material removal was studied,and deformed geometric module was used in COMSOL to achieve material removal.2.The simulation of single pulse laser ablation was carried out.The temperature variation of electron-lattice system with various laser fluence was investigated by the developed model.The thermal equilibrium time of the electron-lattice system was also investigated.The ablation threshold and spot radius were calculated based on the simulation results.Subsequently,the model was extended to multi-pulse ablation,and the evolution of the electron-lattice temperature was simulated.The thermal accumulation between laser pulses was analyzed,as well as the effect of pulse number on ablation depth.3.Laser ablation of stainless steel under Burst mode was simulated.The effect of laser energy,pulse number and operation mode was investigated.The changes of electron-lattice temperature,ablation depth and crater diameter with various laser fluence and operation mode was analyzed,as well as the thermal effect between sub-pulses.4.Using same laser parameters as the simulation study,the single pulse,multi-pulse and Burst mode ablation experiments were carried out.The evolutions of ablation depth,crater diameter and machining morphology were analyzed.The comparison analysis showed that the simulation results were consistent with the experimental results in the overall trend.The feasibility of the developed model for predicting picosecond laser ablation of stainless steel was verified.Finally,the reasons for the discrepancy were analyzed and optimization solutions were proposed.