Dissimilar friction welding of induction surface-hardened steels and thermochemically treated steels

Results on friction welding of surface-hardened steels are analyzed based on experiments using induction-hardened steels as pivotal component, joined with quench-hardened steels and steels thermochemically treated by carburization and nitriding, respectively. Higher axial pressure needs to be applied, in order to fully expunge the hardened layers from the joining plane. A smooth surface for the burr, without cracks, can be obtained for adequate welding parameters and the burr can be subsequently removed without major risks, immediately after the friction welding process ends. For joining an induction hardened C55 steel with a quenched hardened C55 steel, the maximal friction pressure has to be limited to about 200 N/mm2, in order to avoid materials separations in the centre of the joint. High axial pressures lead to good mechanical characteristic for friction welding an induction-hardened 34CrNiMo6 steel with a carburized 16MnCr5 steel. Friction welding of an induction-hardened C55 steel with a C45 nitrided steel showed that an increase of the friction upset distance to 6 mm favours the complete expulsion of the nitride debris, with positive effects on the quality and mechanical properties of the joint.