Set up of a line for induction hardening in inert atmosphere

In the paper the set-up of an equipment for localized induction hardening is presented and the metallurgical properties of the produced pieces are discussed. The hardening is performed on UNI C45 automotive components with conical shape. The pieces have been obtained by cold deformation followed by annealing and tool machining. The final induction hardening is aimed at producing the minimum distortion, being H7 the allowed coupling tolerance, to avoid any further mechanical grinding after the surface hardening. This can be obtained by accurately choosing treatment conditions. The hardening is done with a pulse generator allowing very short heating and treatment times, embedding the workpieces in nitrogen inert atmosphere to reduce the surface oxidation and carefully controlling composition and microstructure of the steel to be treated. Microstructural investigation was performed with OM, SEM and HV. Some examples of treated components are presented, the surface hardness and case depth values confirm that the proposed process is valuable for automotive components surface hardening.