Material Constitutive Behaviour and Microstructure Study on Aluminium Alloys for Friction Stir Welding

Abstract:

The material constitutive behaviour and microstructure of Aluminium alloys 6082 and 7449 were studied with the Gleeble hot compression test. The novel aspect of the work is that the testing was done at high strain-rates and at temperatures within 5 K of the solidus. The results indicated that the strength was maintained up to near solidus temperatures, with no dramatic strength reduction being observed. There was however, a distinct change in the slope observed with the 7449 results around 720 K. The experimental results were then fit to the Zener-Holloman equation, which describes the relationship between the material flow stress, temperature and strain-rates. The material microstructure of the hot compression test samples was analysed, and the averaged grain size was calculated to compare with friction stir weld nuggets. This will be used to infer the processing conditions that exist in the dynamically recrystallized weld nugget. Finally, a simple model was used to understand how processing conditions affected the deformation behaviour.

• Periodical: Advanced Materials Research (Volumes 89-91)
• Pages: 615-620
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.89-91.615
• Online since: January 2010
• Authors: H. Wang, Paul A. Colegrove, H.M. Mayer, L. Campbell, Joseph D. Robson
• Keywords: Subgrains, Al 6082, Al 7449, Friction Stir Welding Model, High-Temperature, Hot Compression Test, Strain Rate

References

[1] T. Sheppard, A. Jackson: Constitutive equations for use in prediction of flow stress during extrusion of aluminium alloys. Mater. Sci. and Tech. 13-3 (1997), pp.203-209.

DOI: 10.1179/mst.1997.13.3.203

[2] H. Li, Z. Li, F. Guo, L. Meng, X. Liang: Constitutive equation model for hot deformation of Al-Cu-Mg-Ag alloy. Special Casting and Nonferrous Alloys. 28-11 (2008), pp.823-826.

[3] Y-. Yi, J-. Yang, Y-. Lin: Flow stress constitutive equation of 7050 aluminum alloy during hot compression. Journal of Materials Engineering. 4-20 (2007), pp.22-26.

[4] H.J. McQueen, N.D. Ryan: Constitutive analysis in hot working. Mater. Sci. and Eng. A. 322-1-2 (2002), pp.43-63.

[5] H.J. McQueen, W.A. Wong, J.J. Jonas: Discussion of dynamic recovery during hot working. Acta Metallurgica 15-3 (1967), pp.586-588.

DOI: 10.1016/0001-6160(67)90100-9

[6] B. Verlinden, P. Wouters, H.J. McQueen, E. Aernoudt, L. Delaey, S. Cauwenberg: Effect of different homogenization treatments on the hot workability of aluminium alloy AA2024. Mater. Sci. and Eng. A. 123-2 (1990), pp.229-37.

DOI: 10.1016/0921-5093(90)90288-e

[7] C.M. Sellars, W.J.M. Tegart. Hot workability. Int. Met. Rev. 17 (1997), pp.1-24.

[8] P.A. Colegrove, H.R. Shercliff, R. Zettler: Model for predicting heat generation and temperature in friction stir welding from the material properties. Sci. and Tech. of Wel. and Join. 12-4(2007), pp.284-297.

DOI: 10.1179/174329307x197539

[9] R. Nandan, G.G. Roy, T. J. Lienert, T. Debroy: Three-dimensional heat and material flow during friction stir welding of mild steel. Acta Materialia. 55-3(2007), pp.883-895.

DOI: 10.1016/j.actamat.2006.09.009

[10] Information available at: http: /www. gleeble. com/3800. htm.

[11] X-. Li, J. Chen, H-. Zhang: Constitutive model for hot deformation of 6082 aluminum alloy. Chinese Journal of Nonferrous Metals. 18-10(2008), pp.1769-74.

[12] N. Kamp, A. Sullivan, R. Tomasi, J.D. Robson: Modelling of heterogeneous precipitate distribution evolution during friction stir welding process. Acta Materialia. 54-8(2006), pp.2003-14.

DOI: 10.1016/j.actamat.2005.12.024

[13] X. Duan, T. Sheppard: Influence of forming parameters on the final subgrain size during hot rolling of aluminium alloys. Journal of Materials Processing Technology. 130-131(2002), pp.245-9.

DOI: 10.1016/s0924-0136(02)00811-7

[14] F.J. Humphreys, M. Hatherly: Recrystallization and related annealing phenomena. Great British: Pergamon. (1995).

[15] E. Cerri, E. Evangelista, A. Forcellese, H.J. McQueen. Comparative hot workability of 7012 and 7075 alloys after different pretreatments. Mater. Sci. and Eng. A. 197-2(1995), pp.181-198.

DOI: 10.1016/0921-5093(94)09714-3

[16] M. Dumont, A. Steuwer, A. Deschamps, M. Peel, P.J. Withers. Microstructure mapping in friction stir welds of 7449 aluminium alloy using SAXS. Acta Materialia. 54-18(2006), pp.4793-4801.

DOI: 10.1016/j.actamat.2006.06.015