Research Topic

Project Description

Strength parameters of highly loaded gears are usually set by case hardening. In recent years, carbonitriding has emerged as a very effective process for producing the highest surface layer strength of case-hardened gears. The simultaneous modification of the surface layer with carbon and nitrogen leads to the formation of a significantly higher retained austenite content after hardening. The metastability of the retained austenite can lead to microcracks under oscillating load due to its transformation and subsequently to a failure of the component under load. In the research project, the solution of the stability problem of retained austenite under oscillating load is to be investigated on the basis of experimental results. For this purpose, the metastable states are to be used to specifically anticipate cold hardening, so that an increase in reproducibility and optimisation of the strength can be achieved. The residual austenite transformation is to be stimulated by targeted blasting and/or deep rolling in advance, and the damaging micro residual stresses generated by this are to be reduced by stress relieving at low temperatures. The tooth root and flank load-carrying capacity is to be increased by the conditioned retained austenite content.