Influence of Joint Angle on Residual Stress, Microstructural Evolution, and Mechanical Performance of Friction Stir Welded AA6061 Aluminum Alloy Using a Novel Adjustable Angled-Joint Fixture

Articles in Press

Document Type : Research Paper

Authors

Faculty of Mechanical Engineering, University of Kashan, Kashan, Iran

Abstract

Friction stir welding (FSW) is a solid-state joining technique capable of producing high-quality joints through frictional heating and severe plastic deformation below the melting point. In this study, the effect of joint angle on the residual stress evolution and integrated mechanical response of AA6061 aluminum alloy was experimentally investigated. Rolled plates (185 × 100 × 4 mm) were annealed prior to welding to improve ductility and material flow. A novel adjustable fixture enabled the fabrication of joints at 90°, 150°, 165°, and 180°, while welding was performed at 1400 rpm and 16 mm/min using angle-specific tools. Residual stresses were quantified using a hybrid digital image correlation–incremental hole drilling (DIC–IHD) method. Microstructural characterization and through-thickness microhardness measurements were conducted to elucidate thermo-mechanical behavior, and tensile tests were performed to evaluate joint performance. Increasing the joint angle progressively reduced tensile residual stresses from 189.5 and 177.3 MPa at 90° to 159.3 and 150.3 MPa at 180° in longitudinal and transverse directions, respectively. The 165° configuration exhibited the most homogeneous microstructure, uniform hardness distribution, and superior tensile strength. The results demonstrate that joint angle governs material flow symmetry and recrystallization behavior, leading to an optimal thermo-mechanical condition at 165° for enhanced structural performance.

Keywords

References

[1] Shah, P. H., & Badheka, V. J. (2019). Friction stir welding of aluminium alloys: An overview of experimental findings–Process, variables, development and applications. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, 233(6), 1191-1226.‏ https://doi.org/10.1177/1464420716689588
[2] Mishra, R. S., & Ma, Z. Y. (2005). Friction stir welding and processing. Materials Science and Engineering: R: Reports, 50, 1-78. https://doi.org/10.1016/j.mser.2005.07.001  
[3] Lohwasser, Daniela, and Zhan Chen, eds. Friction stir welding: From basics to applications. Elsevier, 2009.
[4] Robi, P. S., Pal, S., & Parida, B. (2018). 22 Recent trends and advances in friction stir welding and friction stir processing of metals.
[5] Beygi, R., Zarezadeh Mehrizi, M., Akhavan-Safar, A., Mohammadi, S., & da Silva, L. F. (2023). A parametric study on the effect of FSW parameters and the tool geometry on the tensile strength of AA2024–AA7075 joints: microstructure and fracture. Lubricants, 11(2), 59. https://doi.org/10.3390/lubricants11020059
[6] Prodkornburee, T., & Uthaisangsuk, V. (2025). Modeling of tensile properties and failure of friction stir welded dissimilar aluminum alloys coupled with process-induced defects. The International Journal of Advanced Manufacturing Technology, 136(7), 3263-3284. https://doi.org/10.1007/s00170-025-15001-3
[7] Thilagham, K.T., & Noorullah, D. (2025). Aluminum alloys based on response surface methodology optimization and categorization of FSW for AA7075 & AA6082. Smart Science, 13, 1-15. https://doi.org/10.1080/23080477.2024.2445319
[8] Garcia Ruano, S. A., Delijaicov, S., & dos Santos Junior, A. A. (2023). Acoustoelasticity to measure residual stresses in plates of 5052 aluminum joined by FSW. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 45(2), 82. https://doi.org/10.1007/s40430-022-03998-7
[9] Vahidshad, Y., Rasfijani, A., & Abbasi, A. (2025). The effect of FSW parameters on residual stresses in aluminum alloy using finite element analysis. Space Science, Technology and Applications, e229773. https://doi.org/10.22034/jssta.2025.506404.1232
[10] Salvati, E., Everaerts, J., Kageyama, K., & Korsunsky, A. M. (2019). Transverse fatigue behaviour and residual stress analyses of double sided FSW aluminium alloy joints. Fatigue & Fracture of Engineering Materials & Structures, 42(9), 1980-1990. https://doi.org/10.1111/ffe.13068
[11] Yaowu, X. U., & Rui, B. A. O. (2017). Residual stress determination in friction stir butt welded joints using a digital image correlation-aided slitting technique. Chinese Journal of Aeronautics, 30(3), 1258-1269. https://doi.org/10.1016/j.cja.2016.11.003
[12] Chatterjee, A., Mandal, A., & Giri, A. (2024). A study on residual stress measurement by DIC approach in FSW welded AA6082 joints. Procedia Structural Integrity, 60, 13-19. https://doi.org/10.1016/j.prostr.2024.05.027
[13] Manikandan, R., Elatharasan, G., Parthiban, A., Sakthivel, T. G., Gopalakrishnan, T., & Raju, R. (2025). Experimental and computational analysis of thermal and mechanical characteristics in friction stir welding of dissimilar aluminum alloys with varying tool pin geometries. Welding in the World, 69(7), 2003-2029. https://doi.org/10.1007/s40194-025-01975-x
[14] Zhang, Y., Shi, J., Liao, G., Li, R., Peng, J., Kuang, S., & Shen, F. (2025). Effects of tool structure and process parameters in friction stir welding on the temperature and mechanical properties of dissimilar copper–aluminium welded joints. Metals, 15(2), 193. https://doi.org/10.3390/met15020193
[15] Beygi, R., Talkhabi, A. A., Mehrizi, M. Z., Marques, E. A., Carbas, R. J., & da Silva, L. F. (2023). A novel Lap-Butt joint design for FSW of aluminum to steel in tee-configuration: joining mechanism, intermetallic formation, and fracture behavior. Metals, 13(6), 1027. https://doi.org/10.3390/met13061027
[16] Seleman, M. M. E. S., Ahmed, M. M. Z., Ramadan, R. M., & Zaki, B. A. (2022). Effect of FSW parameters on the microstructure and mechanical properties of T-joints between dissimilar Al-alloys. International Journal of Integrated Engineering, 14(1), 1-12. https://doi.org/10.30880/ijie.2022.14.01.001
[17] Liu, S., Chen, F., & Gao, Y. (2025). Effect of Progressive Pin and Pre-set Wires on the Quality of Corner Forming of Al/Cu FSW T-Lap Joints. Journal of Materials Engineering and Performance, 34(15), 15774-15786. https://doi.org/10.1007/s11665-024-10278-z
[18] Jamshidi Aval, H., Serajzadeh, S., & Kokabi, A. H. (2012). Experimental and theoretical evaluations of thermal histories and residual stresses in dissimilar friction stir welding of AA5086-AA6061. The International Journal of Advanced Manufacturing Technology, 61(1), 149-160. https://doi.org/10.1007/s00170-011-3713-8
[19] Astm, E. (2013). 837-13a standard test method for determining residual stresses by the hole-drilling strain-gage method. ASTM International, West Conshohocken.
[20] Buffa, G., Hua, J., Shivpuri, R., & Fratini, L. (2006). Design of the friction stir welding tool using the continuum based FEM model. Materials Science and Engineering: A, 419(1-2), 381-388. https://doi.org/10.1016/j.msea.2005.09.041
[21] Mohd Yasin, M. N. F. (2013). Study on strength of friction stir welded plate in corner joint configuration.
[22] Davis, J. R. (1993). Aluminum and aluminum alloys. ASM international.‏
[23] Hild, F., & Roux, S. (2012). Digital image correlation. Optical methods for solid mechanics. A full-field approach, 367, 183-228.
[24] Setiawan, W., Darmadi, D. B., Suprapto, W., Soenoko, R., & Gunawan Tri, S. (2019). Varied corner joint design aluminium 6061 using friction stir welding. IOP Conference Series: Materials Science and Engineering, 494(1), 012106. https://doi.org/10.1088/1757-899X/494/1/012106
[25] Mohammadzadeh Jamalian, H., Farahani, M., Besharati Givi, M. K., & Aghaei Vafaei, M. (2016). Study on the effects of friction stir welding process parameters on the microstructure and mechanical properties of 5086-H34 aluminum welded joints. The International Journal of Advanced Manufacturing Technology, 83(1), 611-621. https://doi.org/10.1007/s00170-015-7581-5
[26] Abankar, M., Lunetto, V., De Maddis, M., & Russo Spena, P. (2024). Friction stir welding of additively manufactured A20X aluminum alloy: welding process, mechanical properties, and microstructure. The International Journal of Advanced Manufacturing Technology, 135(9), 4635-4652. https://doi.org/10.1007/s00170-024-14747-6
[27] Liu, X., Xie, P., Wimpory, R., Li, W., Lai, R., Li, M., Chen, D., Liu, Y., & Zhao, H. (2019). Residual stress, microstructure and mechanical properties in thick 6005A-T6 aluminium alloy friction stir welds. Metals, 9(7), 803. https://doi.org/10.3390/met9070803
[28] Reddy, G. M., Mastanaiah, P., Murthy, C. V. S., Mohandas, T., & Viswanathan, N. (2006, December). Microstructure, residual stress distribution and mechanical properties of friction-stir AA 6061 aluminium alloy weldments. In Indian Society for Non-Destructive Testing, Hyderabad Chapter, Proc. National Seminar on Non-Destructive Evaluation.‏
Iranian Journal of Materials Forming

Articles in Press, Accepted Manuscript
Available Online from 18 July 2026

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