Skip to main content Accessibility help

Study of microstructure and mechanical property heterogeneity throughout the wall thickness of high strength aluminum alloy thick-wall pipe

  • Gaoyong Lin (a1), Weiyuan Song (a1), Di Feng (a2), Kun Li (a1), Yongping Feng (a3) and Jinxia Liu (a3)...


Differences in pipe wall microstructure at various positions throughout the wall thickness of high strength aluminum alloy thick-wall pipes produced by reverse hot extrusion were investigated. The microstructures of the inner wall (IW), outer wall (OW), and half wall (HW) were compared. Further, heterogeneity in the mechanical properties of the pipe throughout the wall thickness was also investigated. Results revealed that the volume fraction of precipitation was highest at the HW position because of the higher Zn and Mg contents. Further, approximately 26% of grains were recrystallized in the OW position due to the greater strain during extrusion, while the recrystallization fractions of the IW and HW positions were 13% and 21%, respectively. The effects of precipitation strengthening and deformation strengthening contribute to the highest ultimate tensile strength and Vickers hardness of the HW position, and to the higher elongation of the IW and OW positions.


Corresponding author

a)Address all correspondence to this author. e-mail:


Hide All
1.Mondal, C., Mukhopadhyay, A.K., Raghu, T., and Varma, V.K.: Tensile properties of peak aged 7055 aluminum alloy extrusions. Mater. Sci. Eng., A 454, 673 (2007).
2.Dursun, T. and Soutis, C.: Recent developments in advanced aircraft aluminium alloy. Mater. Des. 56, 862 (2014).
3.Su, R., Qu, Y., You, J., and Li, R.: Study on a new retrogression and re-aging treatment of spray formed Al–Zn–Mg–Cu alloy. J. Mater. Res. 31, 573 (2106).
4.Lin, Y.C., Wang, Z.W., He, D.G., Zhou, Y., Chen, M-S., Huang, M-H., and Zhang, J-L.: Effects of pre-treatments on precipitate microstructures and creep-rupture behavior of an Al–Zn–Mg–Cu alloy. J. Mater. Res. 31, 1286 (2016).
5.Feng, D., Wang, G., Chen, H., and Zhang, X.: The effect of grain size inhomogeneity of ingot on dynamic softening behavior and processing map of Al–8Zn–2Mg–2Cu alloy. Met. Mater. Int. 24, 195 (2018).
6.Cong, F., Zhao, G., Jiang, F., Tian, N., and Li, R.: Effect of homogenization treatment on microstructure and mechanical properties of DC cast 7X50 aluminum alloy. Trans. Nonferrous Met. Soc. 25, 1027 (2015).
7.Chen, K., Liu, H., Zhang, Z., Li, S., and Todd, R.: The improvement of constituent dissolution and mechanical properties of 7055 aluminum alloy by stepped heat treatments. J. Mater. Process. Technol. 142, 190 (2003).
8.Huda, Z. and Edi, P.: Materials selection in design of structures and engines of supersonic aircrafts: A review. Mater. Des. 46, 552 (2013).
9.Chen, J., Zhen, L., Shao, W., Dai, S., and Cui, Y.: Through-thickness texture gradient in AA 7055 aluminum alloy. Mater. Lett. 62, 88 (2012).
10.Liu, S., Zhang, Y., Liu, W., Den, Y., and Zhang, X.: Effect of step-quenching on microstructure of aluminum alloy 7055. Trans. Nonferrous Met. Soc. 20, 1 (2010).
11.Liu, S., Li, C., Han, S., Den, Y., and Zhang, X.: Effect of natural aging on quench-induced inhomogeneity of microstructure and hardness in high strength 7055 aluminum alloy. J. Alloys Compd. 625, 34 (2015).
12.She, H., Shu, D., Wang, J., and Sun, B.: Influence of multi-microstructural alterations on tensile property inhomogeneity of 7055 aluminum alloy medium thick plate. Mater. Char. 113, 189 (2016).
13.Prime, M. and Hill, M.: Residual stress, stress relief, and inhomogeneity in aluminum plate. Scripta Mater. 46, 77 (2002).
14.Yan, L., Shen, J., Li, Z., and Li, J.: Effect of deformation temperature on microstructure and mechanical properties of 7055 aluminum alloy after heat treatment. Trans. Nonferrous Met. Soc. 23, 625 (2013).
15.Liu, S., Zhang, X., Chen, M., and You, J.: Influence of aging on quench sensitivity effect of 7055 aluminum alloy. Trans. Nonferrous Met. Soc. 59, 53 (2008).
16.Li, C., Zhang, X., Han, S., Liu, S., and Den, Y.: Effect of aging on quench-induced inhomogeneity of 7085 aluminum alloy thick plate. Chin. J. Nonferrous Met. 46, 2824 (2016).
17.Gu, W., Li, J., and Wang, Y.: Effect of grain size and Taylor factor on the transverse mechanical properties of 7050 aluminium alloy extrusion profile after over-aging. Acta Metall. Sin. 52, 51 (2016).
18.Williams, J.: The effect of material inhomogeneity on the creep deformation of a thick walled pipe. Int. J. Pressure Vessels Piping 11, 1 (1983).
19.Li, M., Yang, Y., Feng, Z., Huang, B., Luo, X., Lou, X., Lou, J., and Ru, J.: Precipitation sequence of η phase along low-angle grain boundaries in Al–Zn–Mg–Cu alloy during artificial aging. Trans. Nonferrous Met. Soc. 24, 2061 (2014).
20.Li, X., Hansen, V., Gjønnes, J., and Wallenberg, L.: HREM study and structure modeling of the η′ phase, the hardening precipitates in commercial Al–Zn–Mg alloy. Acta Mater. 47, 2651 (1999).
21.She, H., Shu, D., Chu, W., Wang, J., and Sun, B.: Microstructural aspects of second phases in as-cast and homogenized 7055 aluminum alloy with different impurity contents. Metall. Mater. Trans. A 44, 3504 (2013).
22.Marlaud, T., Deschamps, A., Bley, F., Lefebvre, W., and Barouxa, B.: Influence of alloy composition and heat treatment on precipitate composition in Al–Zn–Mg–Cu alloys. Acta Mater. 58, 248 (2010).
23.Lakshminarayanan, A. and Balasubramanian, V.: Process parameters optimization for friction stir welding of RDE-40 aluminium alloy using Taguchi technique. Trans. Nonferrous Met. Soc. 18, 548 (2008).
24.Liu, Y., Jiang, D., Li, B., Ying, T., and Hu, J.: Heating aging behavior of Al–8.35Zn–2.5Mg–2.25Cu alloy. Mater. Des. 60, 116 (2014).
25.Feng, D., Zhang, X., Liu, S., Wu, Z., Guo, Y., and Yu, W.: Inhomogeneity of microstructure and properties of 7A55 aluminium alloy thick plate. J. Cent. South Univ. 46, 2824 (2015).
26.Lee, J., Kim, B., and Kang, C.: Effects of chamber shapes of porthole die on elastic deformation and extrusion process in condenser tube extrusion. Mater. Des. 26, 327 (2005).
27.Starink, M. and Wang, S.: A model for the yield strength of overaged Al–Zn–Mg–Cu alloys. Acta Mater. 51, 5131 (2003).
28.Liu, Y., Jiang, D., Xie, W., Hu, J., and Ma, B.: Solidification phases and their evolution during homogenization of a DC cast Al–8.35Zn–2.5Mg–2.25Cu alloy. Mater. Char. 93, 173 (2014).



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed