Laser marking metal, method 1: Annealing
During annealing, you work with a defocused laser beam, allowing you to only add a low temperature of heat to the material. This heat output leads to a local change in the physical structure of the metal, resulting in recolouring. The surface is not damaged – it remains smooth and clean. The process can generate different shades and colours depending on the temperature used.
The marking will disappear again when the metal is reheated to about 200°C.