Friction welding is one of the most reliable joining techniques for various materials due to a high reproducibility, lack of ecological treats and a relatively narrow thermomecanical affected zone. It offers multiple applicative opportunities in various fields – from automotive and manufacturing industries as well as for special destinations – leading to incontestable technical and economical advantages. However, the friction welding of materials with compositional and/or structural gradients is a critical problem due to the high probability of cracks occurrence, the formation of intermetallic phases that increase the brittleness and a high gradient for residual stresses. The paper refers to the particularities of graded welds through which the rotational energy will be transformed by friction into heat in the surface layer with a certain structural morphology, as well as in the core with different characteristics. Experiments have been performed in order to assess the process parameters which provide the optimal friction energy for an adequate plastifiation of the materials. Macro and optical micrographic investigations corroborated with electron microscopy and hardness measurements provide information concerning the hardening of the thermomecanically affected zone and the formation of seam as result of expulsion of the carburized layer.