Process and equipment for carburising a steel workpiece

In a process for carburising a workpiece of steel, in particular case-hardening steel, the workpiece is introduced into a carburising furnace and, in the latter into a carburising gas atmosphere of controllable C level and predetermined composition, carbon black limit and temperature. In the carburising gas atmosphere, a carburisation layer of a carbon content, which decreases from an actual edge value predetermined for the carburisation treatment towards the core of the workpiece, is produced thereon. The actual edge value is then adjusted in a diffusion treatment at diffusion temperature and by diffusion in an inert gas atmosphere to an edge set value predetermined for the workpiece. The workpiece is then introduced into a fluidised-bed furnace, whose fluidised bed is held by the carburising gas atmosphere in a thermodynamic state above the carbon black limit. After the carburisation up to the actual edge value, the carburising gas atmosphere of the fluidised-bed furnace is exchanged for the inert gas atmosphere. During the diffusion treatment, the fluidised bed is held in the fluidised state by the inert gas atmosphere. The diffusion treatment of the workpiece is also carried out in the fluidised-bed furnace.