Experimental and numerical study of multi-pulse picosecond laser ablation on 316 L stainless steel.

An experimental and numerical study on 10 ps laser ablation of 316 L stainless steel up to 400 hundred pulse exposure has been carried out. In this simulation, the material removal threshold temperature has been carefully discussed depending on the different ablation driving mechanisms. The influence of the instantaneous material removal has also been considered which will affect the calculation of the next pulse's absorption. For single-pulse ablation, the simulated ablation threshold F= 0.26 J/cm is close to the fitted experimental result F= (0.29 ± 0.01) J/cm. For multi-pulse ablation, the simulated ablation rate R= 11.4 nm/pulse is close to the fitted experimental result R= (12.4 ± 0.1) nm/pulse under 0.9 J/cm fluence, while the simulated ablation rate R= 19.8 nm/pulse is slightly larger than the fitted experimental result R= (16.1 ± 0.7) nm/pulse at 2.7 J/cm, providing good agreement between theory and experiment for both single and multi-pulse ablation. This study could be used to predict the multi-pulse laser processing performance, especially with the help of a machine learning method to find the best parameters automatically.