This paper reports the effect of Friction Stir Welding on the mechanical properties and microstructure of

6082-T6 Aluminium alloy. The welds were produced using three different transverse speeds of 90, 120

and 150m/min to vary the heat input to the wields. The rotational speed of 750rpm is constant for the

three welds samples, plunge depth of 0.31mm and tool tilt angle of 3 degrees was employed. The

mechanical properties were characterised by the tensile analysis, the microhardness and joint efficiency of

the welded interface. The microstructures, macrostructures, fracture surface and grain sizes were

characterised. The result revealed that tensile strength at the joint interfaces of the three samples was

enhanced as the transverse speed increases from 90m/min to 150m/min. The joint efficiency of the joint

interfaces of the three welded samples increases. The Vickers hardness values at the joint interfaces were

enhanced for the three samples when compared with the base material. This is attributed to the strain

hardening phenomenon. The resulting microstructural characterization shows that good metallurgical

bonding was achieved at the joint interfaces of the welds produced, this is evident with the presence of the

transition lines separating the advancing side from the retreating side of the joint interfaces.