The effect of friction stir welding parameters on the microstructure, defects, and mechanical properties of AA7075-T651 joints

Document Type : Article

Authors

Department of Mechanical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.

Abstract

This study aims to examine how friction stir welding parameters, such as welding speed and rotational rate, affect the microstructure, defects, and mechanical properties of AA7075-T651 aluminum alloy joints. It also assesses the relation of the defects and microstructure to the mechanical properties. Microstructural investigations using optical microscopy (OM) and scanning electron microscopy (SEM) indicated remarkable grain structure variations among the different welding zones. Especially, it was found out that the interface between welding nugget zone (WNZ) and thermo-mechanically affected zone (TMAZ) is a dominant determinant of the mechanical properties of joints. The importance of the interface comes from the fact that it is the most prone region to cracks, micro-cavities and tunneling defects. WNZ and TMAZ interfaces as well as their grain structures can be influenced by the heat generated from the friction between rotating tool and workpiece material. Therefore, coarser grain structures observed at the WNZ-TMAZ interfaces of the samples welded at higher rotational rates or lower welding speeds is due to the greater heat generated in such cases. Besides, microstructural variations in the weld zone affect the hardness and mechanical properties of weld joints. Thus, samples with coarse-grained structures display lower values of yield stress and microhardness.

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Main Subjects


Refrences:
1.Thomas, W.M., Nicholas, E.D., Needham, J.C., Murch, M.G., Templesmith P., and Dawes, C.J. Friction stir welding", G.B. Patent 9125978.8 (1991).
2. Cavaliere, P. and Squillace, A. High temperature deformation of friction stir processed 7075 aluminium alloy", Materials Characterization, 55(2), pp. 136-142 (2005).
3. Cabibbo, M., McQueen, H.J., Evangelista, E., Spigarelli, S., Di Paola, M., and Falchero, A. Microstructure and mechanical property studies of AA6056 friction stir welded plate", Materials Science and Engineering: A, 460, pp. 86-94 (2007).
4. Mishra, R.S. and Ma, Z.Y. Friction stir welding and processing", Mater Sci. Eng. R, 50, pp. 1-78 (2005). 5. Balasubramanian, V., Ravisankar. V., and Reddy, G.M. Inuences of pulsed current welding and post weld aging treatment on fatigue crack growth behaviour of AA7075 aluminium alloy joints", International Journal of Fatigue, 30(3), pp. 405-416 (2008). 6. Ra_, H.K., Ram, G.J., Phanikumar, G., and Rao, K.P. Microstructure and tensile properties of friction welded aluminum alloy AA7075-T6", Materials & Design, 31(5), pp. 2375-2380 (2010). 7. Sharma, C., Dwivedi, D.K., and Kumar, P. E_ect of welding parameters on microstructure and mechanical properties of friction stir welded joints of AA7039 aluminum alloy", Materials & Design, 36, pp. 379-390 (2012). J. Langari and F. Kolahan/Scientia Iranica, Transactions B: Mechanical Engineering 26 (2019) 2418{2430 2429 8. Rajakumar, S., Muralidharan, C., and Balasubramanian, V. Predicting tensile strength, hardness and corrosion rate of friction stir welded AA6061-T 6 aluminium alloy joints", Materials & Design, 32(5), pp. 2878-2890 (2011). 9. Mahmoud, T., Gaafer, A., and Khalifa, T. E_ect of tool rotational and welding speeds on microstructural and mechanical characteristics of friction stir welded A319 cast Al alloy", Materials Science and Technology, 24(5), pp. 553-559 (2008). 10. Xue, P., Xie, G., Xiao, B., Ma, Z., and Geng, L. E_ect of heat input conditions on microstructure and mechanical properties of friction-stir-welded pure copper", Metallurgical and Materials Transactions A, 41(8), pp. 2010-2021 (2010). 11. Ghorbanzade, T., Soltanipour, A., Dehghani, K., and Chabok, A. Microstructural evolutions and mechanical properties of friction stir welded AA2024-3", Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials Design and Applications, 230(1), pp. 75-87 (2016). 12. Barenji, R.V. E_ect of tool traverse speed on microstructure and mechanical performance of friction stir welded 7020 aluminum alloy", Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials Design and Applications, 230(2), pp. 1-11 (2016). 13. Ren, S., Ma, Z., and Chen, L. E_ect of initial butt surface on tensile properties and fracture behavior of friction stir welded Al-Zn-Mg-Cu alloy", Materials Science and Engineering: A, 479(1), pp. 293-299 (2008). 14. Palanivel, R., Laubscher, R., Dinaharan, I., and Murugan, N. Tensile strength prediction of dissimilar friction stir-welded AA6351-AA5083 using arti_cial neural network technique", Journal of the Brazilian Society of Mechanical Sciences and Engineering, 38(6), pp. 1647- 1657 (2016). 15. Li, B., Shen, Y., and Hu, W. The study on defects in aluminum 2219-T6 thick butt friction stir welds with the application of multiple non-destructive testing methods", Materials & Design, 32(4), pp. 2073-2084 (2011). 16. Hou, X., Yang, X., Cui, L., and Zhou, G. Inuences of joint geometry on defects and mechanical properties of friction stir welded AA6061-T4 T-joints", Materials & Design, 53, pp. 106-117 (2014). 17. Chen, H.B., Yan, K., Lin, T., Chen, S.B., Jiang, C.Y., and Zhao, Y. The investigation of typical welding defects for 5456 aluminum alloy friction stir welds", Materials Science and Engineering: A, 433(1), pp. 64- 69 (2006). 18. Shojaeefard, M.H., Behnagh, R.A., Akbari, M., Givi, M.K.B., and Farhani, F. Modelling and Pareto optimization of mechanical properties of friction stir welded AA7075/AA5083 butt joints using neural network and particle swarm algorithm", Materials & Design, 44, pp. 190-198 (2013). 19. Roshan, S.B., Jooibari, M.B., Teimouri, R., Asgharzadeh-Ahmadi, G., Falahati-Naghibi, M., and Sohrabpoor, H. Optimization of friction stir welding process of AA7075 aluminum alloy to achieve desirable mechanical properties using ANFIS models and simulated annealing algorithm", The International Journal of Advanced Manufacturing Technology, 69(5-8), pp. 1803-1818 (2013). 20. Sevvel, P. and Jaiganesh, V. Characterization of mechanical properties and microstructural analysis of friction stir welded AZ31B Mg alloy thorough optimized process parameters", Procedia Engineering, 97, pp. 741-751 (2014). 21. Fuller, C.B., Mahoney, M.W., Calabrese, M., and Micona, L. Evolution of microstructure and mechanical properties in naturally aged 7050 and 7075 Al friction stir welds", Materials Science and Engineering: A, 527(9), pp. 2233-2240 (2010). 22. Sharma, C., Dwivedi, D.K., and Kumar, P. E_ect of post weld heat treatments on microstructure and mechanical properties of friction stir welded joints of Al-Zn-Mg alloy AA7039", Materials & Design, 43, pp. 134-143 (2013). 23. Shah, P. and Badheka, V. An experimental investigation of temperature distribution and joint properties of Al 7075 T651 friction stir welded aluminium alloys", Procedia Technology, 23, pp. 543-550 (2016). 24. Rao, T.S., Reddy, G.M., and Rao, S.K. Microstructure and mechanical properties of friction stir welded AA7075-T651 aluminum alloy thick plates", Transactions of Nonferrous Metals Society of China, 25(6), pp. 1770-1778 (2015). 25. A. E-112, Standard Test Methods for Determining Average Grain Size, ASTM International USA (2010). 26. Hao, H.L., Ni, D.R., Huang, H., Wang, D., Xiao, B.L., Nie, Z.R., and Ma, Z.Y. E_ect of welding parameters on microstructure and mechanical properties of friction stir welded Al-Mg-Er alloy", Materials Science and Engineering: A, 559, pp. 889-896 (2013). 27. Fratini, L. and Bu_a, G. CDRX modelling in friction stir welding of aluminium alloys", International Journal of Machine Tools and Manufacture, 45(10), pp. 1188-1194 (2005). 28. McNelley, T.R., Swaminathan, S., and Su, J.Q. Recrystallization mechanisms during friction stir welding/ processing of aluminum alloys", Scripta Materialia, 58(5), pp. 349-354 (2008). 29. Frigaard, ?., Grong, ?., and Midling, O.T. A process model for friction stir welding of age hardening aluminum alloys", Metallurgical and Materials Transactions A, 32(5), pp. 1189-1200 (2001). 30. Kim, Y.G., Fujii, H., Tsumura. T., Komazaki, T., and Nakata, K. Three defect types in friction stir welding of aluminum die casting alloy", Materials Science and Engineering: A, 415(1-2), pp. 250-254 (2006). 31. Rajakumar, S., Muralidharan, C., and Balasubramanian, V. Inuence of friction stir welding process and 2430 J. Langari and F. Kolahan/Scientia Iranica, Transactions B: Mechanical Engineering 26 (2019) 2418{2430 tool parameters on strength properties of AA7075-T6 aluminium alloy joints", Materials & Design, 32(2), pp. 535-549 (2011). 32. Ren, S.R., Ma, Z.Y., and Chen, L.Q. E_ect of initial butt surface on tensile properties and fracture behavior of friction stir welded Al-Zn-Mg-Cu alloy", Materials Science and Engineering: A, 479(1-2), pp. 293-299 (2008). 33. Sivaraj, P., Kanagarajan, D., and Balasubramanian, V. E_ect of post weld heat treatment on tensile properties and microstructure characteristics of friction stir welded armour grade AA7075-T651 aluminium alloy", Defence Technology, 10(1), pp. 1-8 (2014). 34. Callister, W.D. and Rethwisch, D.G., Fundamentals of Materials Science and Engineering: An Integrated Approach, John Wiley & Sons (2012). 35. Colligan K. Material ow behavior during friction stir welding of aluminum", Weld J, 78(7), pp. 14-6 (1999). 36. Xu, W., Jinhe Liu, J., Luan, G., and Dong, C. Temperature evolution, microstructure and mechanical properties of friction stir welded thick 2219-O aluminum alloy joints", Materials and Design, 30, pp. 1886-1893 (2009). 37. Xu, W., Jinhe Liu, J., Luan, G., and Dong, C. Microstructure and mechanical properties of friction stir welded joints in 2219-T6 aluminum alloy", Materials and Design, 30, pp. 3460-3467 (2009). 38. Chowdhury, S.M., Chen, D.L., Bhole, S.D., and Cao, X. Tensile properties of a friction stir welded magnesium alloy: E_ect of pin tool thread orientation and weld pitch", Materials Science and Engineering: A, 527(21-22), pp. 6064-6075 (2010). 39. Liu, H.-J., Zhang, H.-J., Huang, Y.-X., and Yu, L. Mechanical properties of underwater friction stir welded 2219 aluminum alloy", Transactions of NonferrousMetals Society of China, 20(8), pp. 1387-1391 (2010).