Abkühlen nach dem Nitrieren/Nitrocarburieren: Phasenumwandlungen von Eisennitriden bei niedrigen Temperaturen

Only little is known of the effect of fine details in the microstructure of the compound (surface) layer (white layer) on the properties of nitrided/nitrocarburized iron-based alloys (steels). It appears certain that the microstructure of the compound layer is of decisive importance for many of the resulting properties. Hence, a tuned optimization of all process parameters is required to achieve the desired combination of property values. The temperature-time path during cooling and the then occurring atmosphere, as well as the temperature during use of the workpiece, can lead to significant microstructural changes in the compound layer. Thus, the dominantly present e and y' phases in the compound layer as produced can be transformed relatively easily, also at low temperatures. These processes and their possible consequences are discussed in this paper.