American Journal of Materials Engineering and Technology, 2016, Vol. 4, No. 1, 11-15 Available online at http://pubs.sciepub.com/materials/4/1/3 © Science and Education Publishing DOI:10.12691/materials-4-1-3 Investigation of Weld Defects in Similar and Dissimilar Friction Stir Welded Joints of Aluminium Alloys of AA7075 and AA6061 by X-ray Radiography Chetan Patil 1 , Hemant Patil 2 , Hiralal Patil 3,* 1 Mechanical Department, PSE, Saki-Palsana, Gujarat, India 2 Mechanical Department, D. N. Patel C.O.E., Shahada, Maharashtra, India 3 Mechanical Department, GDEC, Abrama, Gujarat, India *Corresponding author: hspatil28@gmail.com Abstract 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 AA7075T 651 aluminium alloy and dissimilar friction stir welds between aluminium alloys AA7075T 651 and AA6061T 6 . 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. Keywords: FSW, rotation speed, transverse speed, radiography Cite This Article: Chetan Patil, Hemant Patil, and Hiralal Patil, “Investigation of Weld Defects in Similar and Dissimilar Friction Stir Welded Joints of Aluminium Alloys of AA7075 and AA6061 by X-ray Radiography.” American Journal of Materials Engineering and Technology, vol. 4, no. 1 (2016): 11-15. doi: 10.12691/materials-4-1-3. 1. Introduction Friction Stir Welding (FSW), a solid state joining process was developed and patented by The Welding Institute (TWI) in 1991 [1]. This, which is currently being developed for difficult to- weld high strength aluminium alloys such as 2xxx and 7xxx series Over the last decade, frictions stir welding (FSW) has offered excellent welding quality to the joining of many alloys such as aluminum alloys [2,3] magnesium alloys [4] , Copper alloys [5], and steel alloys [6,7]. It is a new and promising welding process which welds the material below its melting temperature and it has shown superior features such as excellent joint performance, mechanical properties and low energy consumption. However many defects like porosity, kissing bong, solid inclusion and linear crack cavity or groove like defects, large mass of flash out are reported due to improper heat input during the process [8,9]. It reduces the quality of weld joints and impacts the manufacturing cost. Thus it is required to detect the defects in FSW by using non-destructive test method. Non-destructive testing (NDT) is based on techniques that rely on the application of physical principles to determine the characteristics of materials and to detect and assess flaws or harmful defects without change of the usefulness or serviceability of materials [10]. There is a broad range of NDT methods based on different physical principles like ultrasonic, eddy currents evaluation, X-radiography, magnetic particles inspection and dye penetrant application. M. Moles et al [11] used ultrasonic and eddy currents arrays for inspection of friction stir welds in aluminum. L .S. Rosado et al [12] used eddy current probe to detect the imperfections in the friction stir welding of metals. Lie et al [13] have reported on multiple non- destructive testing methods on the FSW of AA 2219-T6. Hu et al [14] also employed a high-precision magnetic sensor to detect the weld defects in aluminium Friction stir welds. In this paper, X- radiography methods are used to study the defects in FSW. Radiography can detect flaws or discontinuities in welds such as cold lap, porosity, incomplete penetration or lack of penetration (lop), incomplete fusion, and internal concavity or suck back, internal & external undercut offset or mismatch, inadequate & excess weld reinforcement and cracks. Radiography technique is based upon exposing the components to short wavelength radiations in the form of X-rays of wavelength less than 0.001x10 -8 cm to about 40x10 -8 cm from a suitable source. The portion of the weldments where defects are suspected is exposed to X- rays emitted from the X-ray tube. During exposure, X-rays penetrate the welded object and thus affect the x-ray film.