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Bobbin friction stir welding (BFSW) is a variant of the conventional friction stir welding (CFSW); it can weld the upper and lower surface of the work-piece in the same pass. This technique involves the bonding of materials without melting. In this work, the influence of tool design on the mechanical properties of welding joints of 6061-T6 aluminum alloy with 6.25 mm thickness produced by FSW bobbin tools was investigated and the best bobbin tool design was determined. Five different probe shapes (threaded straight cylindrical, straight cylindrical with 3 flat surfaces, straight cylindrical with 4 flat surfaces, threaded straight cylindrical with 3 flat surface and threaded straight cylindrical with 4 flat surfaces) with various dimensions of the tool (shoulders and pin) were used to create the welding joints. The direction of the welding process was perpendicular to the rolling direction for aluminum plates. Tensile and bending tests were performed to select the right design of the bobbin tools, which gave superior mechanical properties of the welded zone. The tool of straight cylindrical with four flats, 8 mm probe and 24 mm shoulders diameter gave better tensile strength (193 MPa), elongation (6.1%), bending force (5.7 KN), and welding efficiency (65.4%) according to tensile strength.
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 Mishra R. S., Ma Z. Y., “Friction stir welding and processing”, Materials Science and Engineering R 50 (2005) pp. 1–78.
 W. M. Thomas, E. D. Nicholas, M.G. Needham, and D. J. Templesmith, “Friction Stir Butt Welding”, International Patent Application PCT/GB92/02203, GB Patent Application 9125978.8, US Patent 5.460.317, 1991.
 Mohammad K. Sued and Dirk J. Pons, “Dynamic Interaction between Machine, Tool, and Substrate in Bobbin Friction Stir Welding”, International Journal of Manufacturing Engineering Vol. 2016, Article ID 8697453, 14 pages.
 R. S. Mishra P. S. De and N. Kumar, “Friction Stir Welding and Processing Science and Engineering”, Springer, 2014.
 P. L. Threadgill, M. M. Z Ahmed, J. P. Martin, J. G. Perrett and B. P. Wynne, “The use of bobbin tools for friction stir welding of aluminum alloys”, Materials Science Forum Vols. 638-642 (2010) pp. 1179-1184.
 T. Neumann, R. Zettler, P. Vilaca, J. F. dos Santos, and L. Quintino, “Analysis of self-reacting friction stir welds in a 2024-T351 alloy”, Friction Stir Welding and Processing IV, pp. 55-72, 2007.
 M. K. Sued, D. Pons, J. Lavroff, and E. H. Wong, “Design features for bobbin friction stir welding tools: Development of a conceptual model linking the underlying physics to the production process”, Materials and Design 54 (2014) pp. 632–643.
 W. M. Thomas, C. S. Wiesner, D. J. Marks, and D. G. Staines, “Conventional and bobbin friction stir welding of 12% chromium alloy steel using composite refractory tool materials”, Science and Technology of Welding and Joining, Vol. 14, pp. 247-53, 2009.
 W. Thomas and C. S. Wiesner, “Recent Developments of FSW Technologies: Evaluation of Root Defects, Composite Refractory Tools for Steel joining and One-Pass Welding of Thick Sections Using Self-Reacting Bobbin Tools”, In Trends in Welding Research, Proceedings of the 8th International Conference, 2009.
 J. C. Hou, H. J. Liu, and Y. Q. Zhao, “Influence of rotational speed on microstructures and mechanical properties of 6061-T6 aluminum alloy joints fabricated by self-reacting friction stir welding tool”. International Journal of Advanced Manufacturing technology, July, 2014 73, pp. 1073-1079.
 H. J. Liu, J. C. Hou, and H. Guo, “Effect of welding speed on microstructure and mechanical properties of self-reacting friction stir welded 6061-T6 aluminum alloy”, Material and Design 50 (2013) pp. 872-878.
 W. Y. Li, T. Fu, L. Hutsch, J. Hilgert, F. F. Wang, J. F. Santos and N. Huber, “Effect of rotational speed on microstructure and mechanical properties of bobbin-tool friction-stir welded Mg AZ31”, Material and Design 64 (2014) pp. 714-720.
 L Zhou, G. H. Li, C. L. Liu, J. Wang, Y. X. Huang and J. C. Feng, “Effect of rotational speed on microstructure and mechanical properties of self-reacting friction stir welded Al-Mg-Si alloy”, International Journal of Advanced Manufacturing technology, August, 2016.
 F. F. Wang, W. Y. Li, J. Shen, S. Y. Hu and J. F. Santos, Effect of tool rotational speed on microstructure and mechanical properties of bobbin friction stir welding of Al-Li alloy. Material and Design 86 (2015) pp. 933-940.
 Standard Specification for Aluminum and Aluminum Alloy ASTM Sheet and Plate, ASTM B209, 2004.
 Akos Meilinger, and Imre Torok, “The importance of friction stir welding tool. Production Processes and Systems”. Vol. 6. (2013) No. 1, pp. 25-34.
 Heat treatment of Tool steels, Heat Treating, ASM, Vol.4, 1991.
 Yan Guanghua, Huang Xinmin, Wang Yanqing, Qin Xingguo, Yang Ming, Chu Zuoming and Jin Kang, “Effects of heat treatment on mechanical properties of H13 steel”, Metal Science and Heat Treatment, Vol. 52, 2010, pp. 393-396.
 Sameer S. Chaudhary and Kaushal H. Bhavsar, “A review of Bobbin Tool Friction Stir Welding (FSW) Process”, International Journal of Science Technology & Engineering, Vol. 2, April, 2016, pp. 630-633.
 J. C. McClure, E. Coronado, S. Aloor, B. Nowak, L. M. Murr, and A.C. Nunes, Jr., “Effect of pin tool shape on metal flow during friction stir welding”, In: Trends in Welding Research, Proceedings, 2003, pp. 257–261.
 Y.H. Zhao, Lin S. Wul, and F. X. Qu, “The influence of pin geometry on bonding and mechanical properties in friction stir weld 2014 Al alloy”, Material Letters, Vol. 59, October 2005, pp. 2948-2952.
 S. J. Vijay and N. Murugan, “Influence of tool pin profile on the metallurgical and mechanical properties of friction stir welded Al–10 wt. % TiB2 metal matrix composite”, Material and Design, Vol. 31, August, 2010, pp. 3585-3589.
 amshidi Aval H., Serajzadeh S, and Kokabi A. H., “The influence of tool geometry on the thermo-mechanical and microstructural behavior in friction stir welding of AA5086. In: Proceedings of the institution of mechanical engineers, part c”. Journal of Mechanical Engineering Science, Vol. 225, 2011. pp. 1–16.
 Eladio Amaro Camacho Andrade, “Development of the Bobbin-Tool for Friction Stir Welding Characterization and analysis of aluminum alloy processed AA 6061-T4”, Institute Superior Technical, Lisbon, Portugal, 2010.
 A. Arora, A. De and T. Debroy,“Toward optimum friction stir welding tool shoulder diameter”, Scripta Materialia, Vol. 64, January, 2011, pp. 9-12.
 Elangovan K, Balasubramanian V. Influences of tool pin profile and tool shoulder diameter on the formation of friction stir processing zone in AA6061 aluminum alloy. Mater Des 2008;29:362–73.
 Colligan KJ, Mishra RS. A conceptual model for the process variables related to heat generation in friction stir welding of aluminum. Scripta Mater 2008;58:327–31.
 Padmanaban G, Balasubramanian V. Selection of FSW tool pin profile, shoulder diameter and material for joining AZ31B magnesium alloy – an experimental approach. Mater Des 2009; 30:2647–56.