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Friction stir welding (FSW) parameters, such as tool material, tool geometry, tilt angle, tool rotational speed, welding speed, and axial force play a major role in the weld quality of titanium alloys. Because of excessive erosion, tool material and geometry play the main roles in FSW of titanium alloys. Therefore, in the present work for the first time, tool material and geometry, tool tilt angle, cooling system and shielding gas effects on macrostructure, microstructure, and mechanical properties of pure titanium weld joint were investigated. Result of this research shows that Ti can be joined by the FSW, using a tool with a shoulder made of tungsten (W) and simple pin made of tungsten carbide (WC). The best conditions for welding were use of compressed air as a cooling system, tool tilt angle of 1°, and a stream of Argon as a shielding medium. Investigation on mechanical properties shows that the tensile strength and the yield strength of the welded joint in the best case could be similar to the corresponding strengths of the base metal.

In the present article, the effect of friction stir welding (FSW) parameters on the weldability and the characteristics of dissimilar weld of aluminum alloys, called AA2024-T4 and AA7075-O are investigated. A number of FSW experiments are carried out to obtain high-quality welds by adjusting the rotational and welding speeds. The weldability and blending of two materials are evaluated by using the macrostructural analysis to observe whether making a notch in a threaded cylindrical tool will lead to a better blend rather than the threaded taper tool or it will have no effects. The mechanical properties of the welds are studied through microhardness distribution and tensile tests. Furthermore, the microstructure analysis is performed to study the influence of the pin profile and the rotational speed on the grain size. Moreover, in the present study, one of the most major goals is to obtain high-quality welds by spending as little expenditure as possible. Therefore, it prevents using complicated and insupportable high welding speed equipments.

This research presents the effect of welding speed on dissimilar joints of AA7075-T6 and AA6061-T6 alloys. The weld quality was evaluated through observations of the macrostructure. The mechanical properties of the welds, including the ultimate strength, the percentage of elongation, and the microhardness variations, were determined for different welding speeds. Also the effect of the positions of the two alloys on the mechanical properties was investigated. In addition, during the friction stir welding (FSW) process, the peak temperatures were measured in order to indicate the relation between the peak temperature and the hardness distribution at the heat-affected zone (HAZ). Accordingly, the influence of the welding speed on the developed grain size was elucidated by the microstructural analysis.

In this paper, the material behaviour and mechanical characteristics of lap joint friction stir welding (FSW) between dissimilar alloys, namely, Cu and Al, is investigated. In order to produce welds of a higher quality, a layer of Cu is anodised on the aluminium alloy. The mechanical and the microstructural characterisations are performed on the welds, which are produced using various welding parameters. Scanning electron microscope with energy dispersive X-ray spectroscopy is used to identify the elemental compositions of phases that are formed. The results reveal that the use of the copper anodised layer prevented formation of brittle intermetallic compounds due to the direct FSW of 6061 aluminium alloy to copper and, as a result, enhanced the weld metallurgical and mechanical properties.

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Friction stir welding (FSW) is a solid state welding process for joining aluminium alloys, has been employed in different industries, and is a new and promising welding process that can produce low-cost and high-quality joints of heat-treatable aluminium alloys because this process uses a non-consumable tool to generate frictional heat in the abutting surfaces and can eliminate some welding defects such as crack and porosity. The various parameters such as rotational speed, welding speed, axial force, and attack angle play vital roles in the FSW process in order to analyse the weld quality. In this research, the impact of processing parameters such as different rotational speed and tool pin profiles on the mechanical, micro-, and macrostructural properties during the FSW process involving the butt jointing of AA7075 T6 is investigated. It is important to note that four-flute and taper threaded pin profiles are utilized and the mechanical characteristics are determined by comparing the ultimate strength, percentage of elongation, and microhardness profiles for different rotational speeds and tool pin profiles.

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