ORIGINAL ARTICLE Experimental and theoretical analysis of friction stir welding of Al–Cu joints Ahmed O. Al-Roubaiy & Saja M. Nabat & Andre D. L. Batako Received: 5 June 2013 /Accepted: 16 December 2013 /Published online: 17 January 2014 # Springer-Verlag London 2014 Abstract This paper presents a study of friction stir welding of aluminium and copper using experimental work and theo- retical modelling. The 5083-H116 aluminium alloy and pure copper were successfully friction-stir-welded by offsetting the pin to the aluminium side and controlling the FSW parame- ters. A theoretical analysis is presented along with key find- ings. The process temperatures are predicted analytically using the inverse heat transfer method and correlated with experimental measurements. The temperature distribution in the immediate surroundings of the weld zone is investigated together with the microstructures and mechanical properties of the joint. This was supported by a finite element analysis using COMSOL Multiphysics. In this study, two rotational speeds were used and a range of offsets was applied to the pin. The microstructure analysis of the joints was undertaken. This revealed some particles of Cu inclusion in the nugget zone. The energy dispersive spectroscopy showed a higher diffusion rate of aluminium towards the interface while copper main- tained a straight base line. Keywords Friction stir welding . Aluminium . Copper . Dissimilar joint . Pin offset 1 Introduction The joining of dissimilar materials is becoming increasingly important in industrial applications [1]. Many emerging ap- plications such as power generation, chemical, petrochemical, nuclear, aerospace, transportation and electronic industries require the joining of dissimilar materials using different methods, especially friction welding and friction stir welding [2]. Due to the different chemical, mechanical and thermal properties of materials, the joining of dissimilar materials presents more challenges than joining similar materials. Kimapong and Watanabe [3] carried out experiments in welding aluminium alloy 5083 to mild steel. They investigat- ed the effects of pin rotation speed and the position of the pin axis on the tensile strength and microstructure of the joint. In their study, maximum tensile strength was obtained when the pin offset was 0.2 mm towards the steel. With large offset, the steel fragments scattering in the aluminium alloy matrix be- come larger in size leading to the formation of voids. However, when joining dissimilar materials using friction stir welding (FSW), the problems arise not only from a mate- rial properties point of view but also from the possibility of the formation of brittle inter-metallic phases and low melting point eutectics. The inter-metallic compounds in an Al–Cu system were found in the friction welding of the oxygen-free copper to pure aluminium and in the cold roll welding of Al/ Cu bimetal [2]. FSW has a greater potential of making high- quality welds with dissimilar material compared to fusion A. O. Al-Roubaiy Materials Engineering Department, College of Engineering, Babylon University, Babylon, Iraq e-mail: ahmed_rubai@yahoo.com S. M. Nabat Materials Engineering Department, College of Engineering, Kufa University, Kufa, Iraq e-mail: ssaamhilla@yahoo.com A. D. L. Batako (*) GERI, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK e-mail: a.d.batako@ljmu.ac.uk Int J Adv Manuf Technol (2014) 71:1631–1642 DOI 10.1007/s00170-013-5563-z