The Friction Stir Welding (FSW) process is suitable to join dissimilar materials. The material temperature does not exceed the solidus temperature during FSW. Hence, high quality joints between dissimilar metals can be produced with minimal intermetallic phase formation. The intermetallic phases can cause embrittlement and also lower the electrical and thermal conductivity across the interface. However, nano-scale intermetallic layers between joining partners have been reported in literature repeatedly, and these play a key role in material bonding. The layer thickness is related to welding temperature via an Arrhenius law. However, the correlation of the process parameters and the interface structure is still a subject of ongoing research.
In this study, the potential of temperature control during FSW in order to improve the joint quality has been analyzed. The influence on and control over intermetallic layer thickness was investigated by welding dissimilar lap joints of aluminium and copper at different temperatures. The temperature was controlled by varying the rotational speed using a PI-controller. The results expand the existing knowledge and prove the applicability of temperature control during FSW of dissimilar metals.