Effect of Travel speed on Joint properties of Dissimilar Metal Friction Stir Welds

This paper reports the effect of traverse speed on joint properties of dissimilar metal friction stir welds between aluminium and copper sheets. Welds in butt joint configurations were produced between 5754 Aluminium Alloy (AA) and C11000 Copper (Cu). The welds were produced at a constant rotational speed of 950 rpm and the traverse speed was varied between 50 and 300 mm/min while all other parameters were kept constant. Microstructural evaluation of the welds revealed that at a constant rotational speed and varying the traverse speed, better mixing of both metals and metallurgical bonding were improved at the lowest traverse speed. The average Ultimate Tensile Strength of the welds decreased as the welding speed increased. Higher Vickers microhardness values were measured at the Thermo-Mechanically Affected Zones (TMAZ) and Stir Zones (SZ) of the welds due to dynamic recrystallization and also due to the presence of intermetallic compounds formed in the joint regions. Unlike with similar metal welds which showed a smooth force feedback curve, it was found that a significant variation in force feedback data was obtained for dissimilar metal welds.