Phenomenological Modeling of Material Removal Mechanisms in High-Power Gas-Laser Cutting of Steels

The problem of increasing the productivity and quality of gas-assisted laser cutting of thick steel plates has become particularly relevant as modern laser systems gain greater power and expand their industrial applications. Despite numerous studies, the physical mechanisms of metal destruction under high-power laser irradiation remain poorly understood, complicating the prediction of cutting conditions and the optimization of technological parameters. The research aims to improve the physical description of the gas-assisted laser-cutting process for steels under high-power laser irradiation and to increase the accuracy of predicting cutting conditions based on process parameters. The article considers the physical mechanisms of gas-assisted laser cutting of steels with laser powers up to 20 kW. It was shown that at high power densities of (10–50)·106 W/cm2, the destruction process differs significantly from cutting with 1 kW lasers. A phenomenological model of kerf formation was proposed that accounts for the periodic penetration of the destruction front and explains the formation of a grooved structure on the cut surface. The existence of two cutting zones was substantiated: an upper zone dominated by metal evaporation and a deeper zone where destruction occurs in the melting mode with oxygen-assisted combustion or only melting when inert gases were used. Analytical relationships for temperatures and destruction rates in both zones were derived, accounting for laser beam defocusing along the cutting depth. Based on these relationships, a method for estimating the maximum cutting speed as a function of metal thickness, focal length, and assist-gas type was proposed. Comparison with experimental data confirms the model’s sufficient accuracy for practical prediction of gas-assisted laser-cutting conditions for steels.