The effect of assist gases on the quality of edge surfaces of Al-Li alloys cut with a pulsed Q-switched CO2 laser

•When cutting with a high power pulsed laser using argon, an optical breakdown of the gas occurs.•Part of the laser power is put into the material through the plasma of an optical discharge in argon (laser-plasma cutting).•Laser-plasma cutting of aluminum-lithium alloys with a thickness of 1.5 and 2 mm provides a low roughness cut at an argon pressure of 0.5 bar.•The spatial structure of the cut surface is grooved when using argon and grainy when using air.•When cutting with air, the plasma torch is not observed, on the samples there is a dross. The effect of assist gases (argon or air) on the quality of edge surfaces of aluminum alloys cut with a pulsed Q-switched CO2 laser was experimentally investigated. Sheets of both Al-Mg-Li and Al-Cu-Li alloys with thicknesses of 1.5 and 2.0 mm were cut. It was found that the morphologies of the cut-edge surfaces were significantly different after cutting with argon and air. For the first time, the cutting process was carried out using a laser-plasma mode, when an optical discharge was maintained in an argon flow. At an argon pressure of 0.5 bar, the cut-edge surfaces were without dross and their roughness were significantly lower than that after cutting with a continuous wave laser. Severance energy levels were similar for both laser-plasma and continuous wave cutting modes.