Numerical simulation of nanosecond laser drilling of 316L stainless steel: addition of laser focus and analysis of manufacturing process

A two-dimensional model of nanosecond laser drilling 316L stainless steel was established with the consideration of laser focus, which was indeed different from the original two-phase flow model without laser focus, especially in the temperature field, velocity field, surface morphology and hole depth. Simulation and experiment of drilling holes with different laser repetition frequencies (100 kHz, 50 kHz and 20 kHz) were carried out. The results show that manufacturing process could divide into three stages: high-efficiency phase, stabilization stage and low-efficiency phase. Meanwhile, the limited number of pulses at 100 kHz, 50 kHz and 20 kHz were obtained, and the values were approximately 289, 367 and 492, respectively. More, the values at 10 kHz and 200 kHz obtained by modeling were very close to those calculated by the fitted equation. All the research provides theoretical, simulation and experimental basis for designing and optimizing parameters on laser surface manufacturing.