Niederdruck-Aufkohlen und Hochdruck-Gasabschrecken: Leistungsvergleich mit konventionellem Einsatzhärten. Diskussion

Compared to conventional case-hardening, low-pressure carburizing in conjunction with high-pressure gas quenching is a relatively new heat treatment technology used as a standard heat treatment method by various manufacturers of car transmissions and by subcontracted heat treatment shops. Process management and benefits and drawbacks compared to conventional case-hardening are extensively dealt with in the relevant literature. However, there is still a lack of comparative studies on the efficiency of both heat treatment methods employed for toothed components. On the basis of a direct comparison of the performance of the two methods, the tooth root fatigue strength of gears has been determined for various gear geometries, case-hardening steels and quenching conditions. The results reveal that the expected positive influence of the oxidation-free surface after low-pressure carburizing does not significantly increase the tooth root fatigue strength. The benefit oxidation-free surface is canceled by various metallographically verifiable detrimental mechanisms. Tooth root fatigue strength can be significantly increased only through intensive shot peening, which is equally effective after both methods.