Numerical modeling and characterization of the laser-matter interaction during high-power continous wave laser perforation of thin metal plates

The phenomena occurring during laser-metal interaction depend on a variety of parameters such as laser wavelength, intensity, and thermophysical and optical properties of the irradiated material. This work comprises a detailed study of the perforation process of thin iron and steel plates under CW laser radiation at a wavelength of 1.07 mu m. Experiments were carried out over a wide range of intensities between 0.1 and 100 kW/cm(2), and with beam radii in the millimeter and centimeter range. Additionally, we describe a method applying contact-free radiative temperature measurements, which allows the measurement of melt-through times without an exact knowledge of the plate's spectral surface emissivity. A detailed numerical model is presented and employed to analyze, interpret, and predict data gathered from the experiments. The model is shown to produce accurate predictions and is in good agreement with experimental data. Furthermore, our results indicate that in the investigated regime perforation is governed by gravitational and surface forces. Based on this hypothesis, a criterion for the onset of the perforation explaining the observed local minimum in the perforation time versus beam radius curve is presented. (C) 2015 Laser Institute of America.