In present research work, friction stir welding of armour grade aluminium alloy, which is having excellent strength to weight ratio, has been done at low heat input rate (rotational speed of 600 rpm, travelling speed of 75 mm/min) and tool tilt angle of 2.5°. Tungsten carbide tool with a shoulder diameter of 15 mm was used to produce the joint. Tensile strength and microhardness of welded sample were measured at three different locations i.e. at the start, middle and end of the weld. The lowest value of tensile strength was obtained at the start of the weld while the maximum tensile strength was observed at middle of the weld and having the value of 378.672 MPa which is 82.32% of base metal along with 15.26% elongation. There is a large gap between the lower and the maximum value of tensile strength. The middle of the weld has less fluctuation in microhardness value as compared to the start and end of the weld. While the maximum value of microhardness was obtained on the advancing side at the start of the weld with the value of 187.4 Hv. Microstructural image shows the presence of craters and segregation in the weld surface. XRD result signify the presence of intermetallic compound Al12Mg17 in the welded zone.