Laser straight cutting bronze sheets: Thermal stress analysis and experiment

Laser straight cutting of bronze sheet is carried out. Temperature and stress fields in the cutting section are simulated using the finite element method. Temperature predictions are validated with the thermocouple measurements. The kerf surfaces are examined using optical and scanning electron microscopes. To prevent the oxidation reactions taking place during the cutting process, nitrogen at high pressure is used as the assisting gas. It is found that high stress levels are generated in the neighborhood of the cut edges due to the high temperature gradients formed in this region. Two stress peaks are observed along the cutting direction: i) one is in the re-cast layer and ii) the other is in the frontal region of the laser beam. The striations formed at the kerf surface have shallow depths and the dross attachment is observed at the edges of the kerf exit, which is associated with the low viscosity of the molten flow and the momentum loss of the assisting gas towards the kerf exit.