An Assessment of the Grain Structure Evolution during Hot Forward Extrusion of Aluminum Alloy 7020

Abstract:

The current investigation is concerned with the grain structure evolution in an Al-Zn alloy (EN AW-7020) during the hot forward extrusion process. In order to analyze that, a miniature hot forward extrusion setup was designed which allows the quenching of the extrusion butt immediately after extrusion. In order to gain a better understanding of the process, the shape of the deformed grains was analyzed and the process was simulated. The shape of these grains was indentified in two directions in the different grain zones, e.g. dead metal zone and shear zone. The FE simulations showing the different grain zones were also illustrated. Simulation results and the micrographs were quite promising to find parameters for simulation models in order to predict grain sizes with the method presented in the current research work.

• Periodical: Key Engineering Materials (Volume 424)
• Pages: 35-41
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.424.35
• Online since: December 2009
• Authors: Annika Foydl, Nooman Ben Khalifa, Alexander Brosius, A. Erman Tekkaya
• Keywords: Aluminum (Al), Extrusion, Finite Element Analysis (FEA), Microstructure

References

[1] E. D. Sweet et al.: Effects of Extrusion Parameters on Coarse Grain Surfache Layer in 6xxx Series Extrusions, ET (2004).

[2] M. Schikorra, L. Donati, L. Tomesani, A.E. Tekkaya: Microstructure analysis of aluminum extrusion: Prediction of microstructure on AA6060 alloy, Journal of Materials Processing Technology, Volume 201 (2008), pp.156-162.

DOI: 10.1016/j.jmatprotec.2007.11.160

[3] H. Mecking , U.F. Kocks: Kinetics of flow and strain-hardening, Acta Metallurgica, Volume 29 (1981), pp.1865-1875.

DOI: 10.1016/0001-6160(81)90112-7

[4] H.J. McQueen, W. Blum: Dynamic recovery: sufficient mechanism in the hot deformation of Al (<99. 99), Materials Science and Engineering A, Volume 290(2000), pp.95-107.

DOI: 10.1016/s0921-5093(00)00933-3

[5] H.J. McQueen: Deficiencies in Continuous DRX Hypothesis as a Substitute for DRX Theory, Materials Forum, Volume 28 (2004), pp.351-356.

[6] S. Gourdet, F. Montheillet: A model of continuous dynamic recrystallization, Acta Materialia, Volume 51 (2003), pp.2685-2699.

DOI: 10.1016/s1359-6454(03)00078-8

[7] W. Blum, Q. Zhu, R. Merkel, H.J. McQueen: Geometric dynamic recrystallization in hot torsion of Al-5Mg-0. 6Mn (AA5083), Materials Science and Engineering A, Volume 205 (1996), pp.23-30.

DOI: 10.1016/0921-5093(95)09990-5

[8] M. Bakhshi-Jooybari: A theoretical and experimental study of friction in metal forming by the use of the forward extrusion process, Journal of Materials Processing Technology, Volume 125-126 (2002), pp.369-374.

DOI: 10.1016/s0924-0136(02)00343-6

[9] M. Schikorra, L. Donati, L. Tomesani, M. Kleiner: The role of friction in the extrusion of AA6060 aluminum alloy, process analysis and monitoring, Journal of Materials Processing Technology, Volume 191 (2007), pp.288-292.

DOI: 10.1016/j.jmatprotec.2007.03.096

[10] S. Kalz: Numerische Simulation des Strangpresse mit Hilfe der Methode der finiten Elemente, Dr. -Ing. Dissertation, Institut für bildsame Formgebung, Aachen, IBSN 3-8265-9718-4 (2001).

[11] T. Kloppenborg, M. Schikorra, M. Schomäcker, A.E. Tekkaya: Numerical Optimization of Bearing Length in Composite Extrusion Processes, Proceedings of International Workshop and Extrusion Benchmark, Bologna (Italy), 20. -21. Sept. 2007, Zürich: Trans Tech Publications Ltd (2008).

DOI: 10.4028/www.scientific.net/kem.367.47

[12] G. Petzow: Metallographisches, Keramographisches, Plastographisches Ätzen, 6. überarbeitete Auflage, Nachdruck, September 2006, Borntraeger, p.72, IBSN 013000170.

DOI: 10.1002/maco.19940451212