The 2 mm thickness sheets of Al-5Mg and technical purity Cu (Cu-ETP) were FSWed to receive butt joints. The geometry of the tool and FSW parameters were determined in order to get sound welds with high level of mechanical properties. Hardness measurements and tensile tests of the welds were provided. The hardness was measured at the welds cross sections and the measured values in stir zones of the dissimilar joints are much higher than of the base materials. Maximum observed average UTS is 214 MPa and average YTS is 147 MPa after tensile tests, maximum observed average elongation is 12%. Therefore, the optimal combination of FSW parameters and tool geometry were set for the butt joint and the influence of the FSW parameters on the properties of the Cu-Al dissimilar materials joints was defined. The technology of Impulse Friction Stir Welding (IFSW) was implemented to receive sound weld of dissimilar materials. The results of hardness profile measurement show the same behavior as hardness profile of the welds received by conventional FSW. The observed average UTS is 129 MPa and average YTS is 80 MPa after tensile tests, the observed average elongation is 8%. It should be proposed that obtained results showed that the additional deformation generated by impulse force during IFSW reduces the weldability of dissimilar Cu-Al joints.
According to the excellent electrical and thermal conductivity, copper and aluminium have a great potential for the different industrial applications. The joining of these two dissimilar materials is efficient due to its technological and economic advantages. Electrical connectors, bus-bars, foil conductor in transformers, capacitor and condenser foil windings, refrigeration tubes, heat-exchangers tubes, tube-sheets, etc. are the common applications of Cu and Al joints (Mehta and Badheka, 2016).
Solid state joining processes are reasonable to use for dissimilar materials joints according to their ability to avoid the formation of large intermetallic compounds (IMCs) in the weld. One of the possible and more useful over the several decades method to receive Cu-Al dissimilar materials joints is a FSW, invented and patented by The Welding Institute (TWI), London, UK, in 1991. The material influenced by the tool during FSW is affected by severe plastic deformation at elevated temperatures (Rudskoi, Naumov and Chernikov, 2014). Severe plastic deformations techniques are characterized by the ultra-fine grains formation and consequently intensive strengthening of the processed materials (Rudskoy, Kodzhaspirov, Kitaeva, Rudaev and Kliber, 2015; Parshikov, Rudskoy, Zolotov and Tolochko, 2013; Rudskoy, 2007). The ultra-fine grain structure guarantees the unique combination of strength and plasticity (Kodzhaspirov and Rudskoy, 2017).
