Abstract

To a large extent, the promising expectations that were set in the 1980s in metal matrix composites, MMCs, have been diluted in recent decades. One reason for this frustration lies in the impossibility of joining these materials by conventional welding methods: these methods (involving fusion) destroy the homogeneous distribution of the reinforcement and give rise to reaction products detrimental to the properties of the joint. Friction stir welding, FSW, however, does not involve fusion, it occurs by a severe plastic deformation process, avoiding the drawbacks of traditional welding techniques. Therefore, recent years have witnessed a growing interest in the study of welds by this technique, not only of MMCs but also of dissimilar welds MMC-monolithic metal. joining MMCs by FSW is not simple, particularly if the reinforcement content is high,> 20 vol%. This paper discusses the most important difficulties facing this welding process and summarizes the recent results of CENIM-AIMEN studies on joints of MMCs with up to 40%vol. of reinforcement, and dissimilar joints. The most relevant correlations between the different mechanical stresses required under different advancing and rotational velocities are presented. This will allow an analysis of the energy balance of the work necessary to produce the deformation of the material and to heat it. In summary, it is emphasized the importance of measuring these efforts to deepen the severe plastic deformation process that takes place, always at high strain rates.