Investigation of Weld Defects in Similar and Dissimilar Friction Stir Welded Joints of Aluminium Alloys of AA7075 and AA6061 by X-ray Radiography

X-ray radiography techniques are used for evaluation of the quality of the friction stir welded aluminium butt joints. This paper reports X-ray radiography testing conducted on similar friction stir welds between AA7075T651 aluminium alloy and dissimilar friction stir welds between aluminium alloys AA7075T651 and AA6061T6. The Friction stir welds of AA7075 & AA6061 aluminium alloy were produced at different tool rotational speeds and transverse speed. The tool rotational speed was varied from 800, 900, 1000 rpm while the transverse speed was varied from 30, 35, 40mm/min. The visual inspection and the x-ray radiographic testing techniques were employed to conduct the tests; these tests were conducted on the welds to ascertain the joint integrity before characterization to have an idea of the quality of the welds. In visual defects, the lateral flash was observed in most of the welds, but the x-ray radiography technique revealed the presence of lack of penetrations flaws in all weld samples and cracks, voids, wormhole defects in some of the welds. It was found that increasing the transverse speed increases the occurrence of weld defects.