Optimized Nitriding for Subsequent Induction Heat Treatment

Abstract Nitriding is used to achieve a high hardness in the surface layer through the precipitation of nitrides. However, to realize high nitriding hardness depths, treatment times of many hours are necessary, which usually also result in a decrease in strength within the nitrided layer and base material. With induction heat treatment, on the other hand, high hardness depths can be achieved in a very short time. However, the maximum hardness increase is limited by the alloy content of the material. By combining nitriding and induction hardening, high hardness depths can be achieved in short treatment times as an alternative to deep nitriding. In addition to a significant saving in process energy surface layer properties that cannot be achieved with the individual processes are expected. In order to fully exploit the potential of the combination treatment, at first suitable conditions must be set during nitriding for the subsequent induction hardening. In the present work, nitriding layers with low-porosity compound layers as well as only diffusion layers were produced and analyzed on typical nitriding and tempering steels for this purpose.