VERFAHREN ZUM AUFKOHLEN EINES WERKSTUECKES AUS STAHL

The process carburizes a steel workpiece, particularly a steel piece made of casehardened steel, to a predetermined surface carbon content in a fluidized bed oven. In a first carburizing step one carburizing gas is used whose carbon content exceeds that corresponding to the surface carbon set or desired content and whose C-level is above the soot limit. Thus an actual surface carbon content is provided which lies above the predetermined surface carbon set or desired content. Then after that in the same fluidized bed oven a diffusion treatment of the workpiece is performed in another carburizing gas which has a C-level above the soot limit, but a reduced carbon content relative to the first carbon containing gas, this carbon content being less than or equal to that corresponding to the surface carbon set or desired content. The described sequence of carburization followed by diffusion treatment is repeated until a predetermined carbon depth or penetration is reached. The surface carbon set or desired content is adjusted in a final diffusion process.