• Jahazi, Mohammad
• Bocher, Philippe
• Zedan, Yasser
• Masoumi, Mahdi

Abstract

In the present research an appropriate tool design is developed for joining of AA2198-T3 and AA2024-T3, subsequently the influence of rotational and traverse speed for the selected tool on the joint tensile properties is evaluated. Three shoulder profiles (flat, spiral, and fan) and five different pin profiles (tapered cylindrical, straight cylindrical, threaded cylindrical, cone, and square) were designed. The weld quality has been evaluated by means of visual inspection, microstructure analysis and tensile tests. Local strain maps measurements using Digital Image Correlation (DIC) enabled to determine weld local properties and determine the joints failure mode during monotonic tensile loading test.Two dimensional hardness map across the cross section through the weld joint was also carried out to further document the heterogeneities of the FSW joint. The tapered cylindrical pin with a fan shoulder was the optimal tool design configuration in terms of mechanical properties. Tensile tests were conducted on the joints produced by optimal tool design at different traverse and rotational speeds. The fracture of samples occurred in the HAZ of the advancing side (AA2198) and in the middle of the joint, which are zones depicting the highest strain values and the lowest hardness values via DIC technique and micro hardness measurements, respectively. Higher traverse speed was found to increase the joint yield strength. The joint efficiency can reach up to 78% by choosing optimum welding speed parameters of 750 rpm and 450 mm/min. Besides, it has been found that although the rotational speed has not a significant effect on the mechanical properties, higher rotational and traverse speeds can enhance the formation of tunneling and kissing bond defects in the joint.

Topics

• impedance spectroscopy
• microstructure
• aluminium
• strength
• hardness
• defect
• yield strength
• joining