Relation of laser parameters in color marking of stainless steel

Color marking of stainless steels as a process is known for sometime but still it has not been used widely in the industry. Some industrial applications have been seen. New MOPA fiber lasers allow independent tuning different laser parameters and the marking process can be optimized for producing colors with better quality and visual appearance. Laser processing of metal surfaces creates an oxide layer on the surface. The thickness of this layer defines how white light is reflected from the sample. What in principle is only a thin oxide layer on the surface can be seen as different colors by the viewer. In this study, the visual appearance of laser marked surfaces was optimized by varying different laser parameters. The aim was to create a uniform oxide layers on the surface which would appear as a high quality color marking. Marking quality was evaluated by visual examination. Relation of different laser parameters to produced color is discussed based on these results. Few application samples are also presented.