Friction stir welding (FSW) currently contributes a significant joining process for welding aluminium, magnesium, and other metals in which no molten or liquid state were involved. It is well known that aluminium alloys are more effective, promising for different applications light weight, strength and low cost. This study aims to determine how such tools geometry and tool speed can be related to dissimilar material in the joining process. Specifically, it investigates whether the distribution of the weld zone particularly between tool pin profile to rotational speed. In this context, the influence of tool pin profile and tool rotational speed in relation to the mechanical properties and microstructure of friction stir welded. The aim of this study is also to test the hypothesis that better mixing between dissimilar metals at higher tool rotational speed along the weld path. Three different tool profiles were configured with AA5083 and AA7075. During welding, notable presence of various types of defects such as voids and wormholes in the weld region. The results of this work showed that the tool pin profile and weld parameter are significant in determining mechanical properties at different tool rotational speed. The highest tensile strength achieved was about 263 MPa and the defectfree joint was obtained by using the threaded tapered cylindrical pin tool at a rotational speed of 800 rpm. These findings indicate that different tool profiles influence differently on the formation of defects at welds. On this basis, the tool geometry should be considered when designing experimental friction stir welded joint.

Friction stir welding is a solid state innovative joining technique, widely being used for joining aluminium alloys in aerospace, marine automotive and many other applications of commercial importance. The welding parameters and tool pin profile play a major role in deciding the weld quality. In this paper, an attempt has been made to understand the influences of welding speed and pin profile of the tool on friction stir welded joints of AA6082-T6 alloy. Three different tool pin profiles (tapered cylindrical four flutes, triangular and hexagonal) have been used to fabricate the joints at different welding speeds in the range of 30 to 74 mm/min. Microhardness (HV) and tensile tests performed at room temperature were used to evaluate the mechanical properties of the joints. In order to analyse the microstructural evolution of the material, the weld’s cross-sections were observed optically and SEM observations were made of the fracture surfaces. From this investigation it is found that the hexagonal tool pin profile produces mechanically sound and metallurgically defect free welds compared to other tool pin profiles.