Friction-stir-welded overaged 7020-T6 alloy joint: an investigation on the effect of rotational speed on the microstructure and mechanical properties

M. Alipour Behzadi; Khalil Ranjbar; R. Dehmolaei; E. Bagherpour

doi:10.1007/s12613-019-1770-4

Volume 26 Issue 5

May 2019

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Article Navigation > International Journal of Minerals, Metallurgy and Materials > 2019 > 26(5): 622-633

M. Alipour Behzadi, Khalil Ranjbar, R. Dehmolaei, and E. Bagherpour, Friction-stir-welded overaged 7020-T6 alloy joint: an investigation on the effect of rotational speed on the microstructure and mechanical properties, Int. J. Miner. Metall. Mater., 26(2019), No. 5, pp. 622-633. https://doi.org/10.1007/s12613-019-1770-4

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M. Alipour Behzadi, Khalil Ranjbar, R. Dehmolaei, and E. Bagherpour, Friction-stir-welded overaged 7020-T6 alloy joint: an investigation on the effect of rotational speed on the microstructure and mechanical properties, Int. J. Miner. Metall. Mater., 26(2019), No. 5, pp. 622-633. https://doi.org/10.1007/s12613-019-1770-4

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Research Article

Friction-stir-welded overaged 7020-T6 alloy joint: an investigation on the effect of rotational speed on the microstructure and mechanical properties

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Corresponding author:
Khalil Ranjbar E-mail: k_ranjbar@scu.ac.ir
Received: 17 July 2018; Revised: 21 November 2018; Accepted: 24 November 2018

Abstract

Abstract

Commercial A7020-T6 plates in the overaged state were subjected to friction stir welding with four different tool rotational speeds of 500, 710, 1000, and 1400 r/min and a single traverse feed rate of 40 mm/min. The resultant changes in the welding heat input, microstructure, and the mechanical properties of the joints were investigated. The changes were related to the processes of growth, dissolution, and re-formation of precipitates. The precipitate evolution was examined by differential scanning calorimetry, and the microstructural analysis was conducted using optical, scanning, and transmission electron microscopes. The results showed that the grain size in the stirred zone (SZ) decreased substantially compared with the base metal, but increased with tool rotational speed because of the rise in temperature. We found that the width of the heat-affected zone increased with tool rotational speed. The hardness and the tensile strength in the SZ increased with increasing heat input compared with the base metal in the overaged condition. This recovery in mechanical properties of the joints can be attributed to the dissolution and re-formation of precipitates in the SZ and the thermomechanically affected zone. This process is referred to as an "auto-aging treatment".
- A7020-T6;
- overaged;
- friction stir welding;
- precipitates;
- rotational speed;
- heat input;
- auto-aging

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References

[1]	R.S. Mishraa and Z.Y. Ma, Friction stir welding and processing, Mater. Sci. Eng. R, 50(2005), No. 1-2, p. 1.
[2]	P.L. Threadgill, A.J. Leonard, H.R. Shercliff, and P.J. Withers, Friction stir welding of aluminium alloys, Int. Mater. Rev., 54(2009), No. 2, p. 49.
[3]	S. Rathee, S. Maheshwari, and A. N. Siddiquee, Issues and strategies in composite fabrication via friction stir processing:a review, Mater. Manuf. Processes, 33(2018), No. 3, p. 239.
[4]	T. Ma and G. den Ouden, Softening behaviour of Al-Zn-Mg alloys due to welding, Mater. Sci. Eng. A, 266(1999), No. 1-2, p. 198.
[5]	M.G. Mousavi, M.J.M. Hermans, I.M. Richardson, and G. den Ouden, Grain refinement due to grain detachment in electromagnetically stirred AA7020 welds, Sci. Technol. Weld. Joining, 8(2003), No. 4, p. 309.
[6]	G.Çam, Friction stir welded structural materials:beyond Al-alloys, Int. Mater. Rev., 56(2011), No. 1, p. 1.
[7]	K. Dehghani, R. Ghorbani, and A.R. Soltanipoor, Microstructural evolution and mechanical properties during the friction stir welding of 7075-O aluminum alloy, Int. J. Adv. Manuf. Technol., 77(2015), No. 9-12, p. 1671.
[8]	G.Çam and S. Mistikoglu, Recent developments in friction stir welding of Al-alloys, J. Mater. Eng. Perform., 23(2014), No. 6, p. 1936.
[9]	R.S. Mishra and Z.Y. Ma, Friction stir welding and processing, Mater. Sci. Eng. R, 50(2007), No. 1-2, p. 1.
[10]	A.S. Golezani, R.V. Barenji, A. Heidarzadeh, and H. Pouraliakbar, Elucidating of tool rotational speed in friction stir welding of 7020-T6 aluminum alloy, Int. J. Adv. Manuf. Technol., 81(2015), No. 5-8, p. 1155.
[11]	K. Kumar, S.V. Kailas, and T. Srivatsan, The role of tool design in influencing the mechanism for the formation of friction stir welds in aluminum alloy 7020, Mater. Manuf. Processes, 26(2011), No. 7, p. 915.
[12]	M.W. Mahoney, C.G. Rhodes, J.G. Flintoff, W.H. Bingel, and R.A. Spurling, Properties of friction-stir-welded 7075 T651 aluminum, Metall. Mater. Trans. A, 29(1998), No. 7, p. 1955.
[13]	G.İpekoğlu, S. Erim, and G.Çam, Effects of temper condition and post weld heat treatment on the microstructure and mechanical properties of friction stir butt-welded AA7075 Al alloy plates, Int. J. Adv. Manuf. Technol. 70(2014), No. 1-4, p. 201.
[14]	K.V. Jata, K.K. Sankaran, and J.J. Ruschau, Friction-stir welding effects on microstructure and fatigue of aluminum alloy 7050-T7451, Metall. Mater. Trans. A, 31(2000), No. 9, p. 2181.
[15]	J.Q. Su; T.W. Nelson, R. Mishra, and M. Mahoney, Microstructural investigation of friction stir welded 7050-T651 aluminium, Acta Mater., 51(2003), No. 3, p. 713.
[16]	A.M. Gaafer, T.S. Mahmoud, and E.H. Mansour, Microstructural and mechanical characteristics of AA7020-O Al plates joined by friction stir welding, Mater. Sci. Eng. A, 527(2010), No. 27, p. 7424.
[17]	Y.S. Sato, M. Urata, and H. Kokawa, Parameters controlling microstructure and hardness during friction-stir welding of precipitation-hardenable aluminum alloy 6063, Metall. Mater. Trans. A, 33(2002), No. 3, p. 625.
[18]	M.C. Paulisch, N. Wanderka, M. Haupt, S. Selve, I. Driehorst, and W. Reimers, I. Driehorst and W. Reimers, The influence of heat treatments on the microstructure and the mechanical properties in commercial 7020 alloys, Mater. Sci. Eng. A, 626(2015), p. 254.
[19]	C. Hamilton, S. Dymek, and O. Senkov, Characterisation of friction stir welded 7042-T6 extrusions through differential scanning calorimetry, Sci. Technol. Weld. Joining, 17(2012), No. 1, p. 42.
[20]	P.A. Colegrove and H.R. Shercliff, Experimental and numerical analysis of aluminium alloy 7075-T7351 friction stir welds, Sci. Technol. Weld. Joining 8(2003), No. 5, p. 360.
[21]	R.S. Mishra, P.S. De, and N. Kumar, Friction Stir Welding and Processing, Springer International Publishing, Switzerland, 2014, p. 227.
[22]	J.H. Yan, M.A. Sutton, and A.P. Reynolds, Process-structure-property relationships for nugget and heat affected zone regions of AA2524-T351 friction stir welds, Sci. Technol. Weld. Joining, 10(2005), No. 6, p. 725.
[23]	C.B. Fuller, M.W. Mahoney, M. Calabrese, and L. Micona,Evolution of microstructure and mechanical properties in naturally aged 7050 and 7075 Al friction stir welds, Mater. Sci. Eng. A, 527(2010), No. 9, p. 2233.
[24]	R.W. Fonda, J.F. Bingert, and K.J. Colligan, Development of grain structure during friction stir welding, Scripta Mater., 51(2004), No. 3, p. 243.
[25]	T.R. McNelley, S. Swaminathan, and J.Q. Su, Recrystallization mechanisms during friction stir welding/processing of aluminum alloys, Scripta Mater., 58(2008), No. 5, p. 349.
[26]	Z.Y. Ma, S.R. Sharma, and R.S. Mishra, Effect of friction stir processing on the microstructure of cast A356 aluminum, Mater. Sci. Eng. A, 433(2006), No. 1-2, p. 269.
[27]	K. Kumar and S.V. Kailas, The role of friction stir welding tool on material flow and weld formation, Mater. Sci. Eng. A, 485(2008), No. 1-2, p. 367.
[28]	H. Jin, S. Saimoto, M. Ball, and P.L. Threadgill, Characterisation of microstructure and texture in friction stir welded joints of 5754 and 5182 aluminium alloy sheets, Mater. Sci. Technol., 17(2001), No. 12, p. 1605.
[29]	Z. Zhang and D.L. Chen, Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites, Mater. Sci. Eng. A, 483-484(2008), p. 148.