A Novel Method for the Determination of High Temperature FLCs of ECAP-Processed Aluminum AA5083 Sheet Metal

Abstract:

In this study, investigations into the deformation behavior of aluminum AA5083 at elevated temperatures were carried out on a newly developed test rig. The test rig was developed jointly with ZwickRoell GmbH & Co. KG (Germany) and is based on a Nakajima test carried out with heated dies. In this way, statements can be made about the lightweight potential of the alloy. Additionally, equal-channel angular pressing (ECAP) was performed to process the aluminum sheet metal. The conventional ECAP process is mainly used for bulk material in laboratory use and therefore is often not suitable for many industrial applications, especially for large series. The use of sheet metal allows a significant increase in the areas of application. It is documented in conventional ECAP that grain refinement is achieved by the severe plastic deformation. At room temperature this primarily increases the mechanical strength. Formability is improved in fine-grained materials, especially at elevated temperatures, which is related to diffusion-controlled deformation mechanisms and grain boundary sliding. The advantages of ECAP for sheet materials are thus also in lightweight construction and can even optimize the use of the AA5083 alloy. ECAP-route C was used for the process to provide the most homogeneous microstructure possible (180° rotation around the ECAP-axis after the first pass). Nakajima specimens were taken from the processed sheet materials to determine the Forming Limit Curve (FLC) compared to the reference material (four different specimen geometries). FLCs under elevated temperatures (250 °C, 375 °C) were performed on the novel Nakajima test bench. A special feature of the test rig is the rapid heating to avoid microstructural changes. Microscopic examinations were performed after the deformation to study the deformation mechanisms. Differences of the forming and fracture mechanisms between the reference alloy and the ECAP material were found.

• Periodical: Key Engineering Materials (Volume 926)
• Pages: 1039-1050
• DOI: https://doi.org/10.4028/p-w5x675
• Online since: July 2022
• Authors: Maximilian Gruber*, Philipp Leitner, Matthias Auer, Christian Illgen, Philipp Frint, Martin F.X. Wagner, Wolfram Volk
• Keywords: Aluminum AA5083, Equal-Channel Angular Pressing (ECAP), Hot Forming Limit Curve (FLC)

References

[1] F. Ostermann, Anwendungstechnologie Aluminium, Berlin, Heidelberg: Springer Berlin Heidelberg, (2014).

[2] H. Ribes, Aluminum Applications in Lightweight Design for Small Commercial Vehicles and Station Wagons, ATZprod worldwide, 2019, no. 6:42–45.

DOI: 10.1007/s38312-019-0004-0

[3] P.F. Bariani, S. Bruschi, A. Ghiotti, and F. Michieletto, Hot stamping of AA5083 aluminium alloy sheets, CIRP Annals, 62 (2013), 251–254.

DOI: 10.1016/j.cirp.2013.03.050

[4] R. Neugebauer, T. Altan, M. Geiger, M. Kleiner, and A. Sterzing, Sheet metal forming at elevated temperatures, CIRP Annals, 55 (2006), 793–816.

DOI: 10.1016/j.cirp.2006.10.008

[5] K. Siegert, Blechumformung, Berlin, Heidelberg: Springer Berlin Heidelberg, (2015).

[6] T.G. Langdon, The mechanical properties of superplastic materials, Metallurgical Transactions A, 13A (1982), 689–701.

[7] F. Klocke, and W. König, Fertigungsverfahren 4: Umformen, SpringerLink Bücher, Berlin, Heidelberg: Springer Berlin Heidelberg, (2006).

[8] M. Kawasaki, and T.G. Langdon, Principles of superplasticity in ultrafine-grained materials, Journal of Materials Science, 42 (2007), 1782–1796.

DOI: 10.1007/s10853-006-0954-2

[9] M.F.-X. Wagner, N. Nostitz, S. Frint, P. Frint, and J. Ihlemann, Plastic flow during equal-channel angular pressing with arbitrary tool angles, International Journal of Plasticity, 134 (2020).

DOI: 10.1016/j.ijplas.2020.102755

[10] J. Suh, J. Victoria-Hernandez, D. Letzig, R. Golle, S. Yi, J. Bohlen, and W. Volk, Improvement of Ductility at Room Temperature of Mg-3Al-1Zn Alloy Sheets Processed by Equal Channel Angular Pressing, Procedia Engineering, 81 (2014), 1517–1522.

DOI: 10.1016/j.proeng.2014.10.183

[11] M. Gruber, C. Illgen, P. Frint, M.F.-X. Wagner, and W. Volk, Numerical and Experimental Study on ECAP-Processing Parameters for Efficient Grain Refinement of AA5083 Sheet Metal, Key Engineering Materials, 794 (2019), 315–323.

DOI: 10.4028/www.scientific.net/kem.794.315

[12] P. Frint, M.F.-X. Wagner, S. Weber, S. Seipp, S. Frint, and T. Lampke, An experimental study on optimum lubrication for large-scale severe plastic deformation of aluminum-based alloys, Journal of Materials Processing Technology, 239 (2017), 222–229.

DOI: 10.1016/j.jmatprotec.2016.08.032

[13] M. Gruber, Y. Yang, C. Illgen, P. Frint, M.F.-X. Wagner, and W. Volk, Thermomechanical Analysis and Experimental Validation of ECAP for Aluminum Sheet Metal, Forming the Future, ed. G. Daehn et al., The Minerals, Metals & Materials Series, vol. 1, Cham: Springer International Publishing, 2021, 1775–1790.

DOI: 10.1007/978-3-030-75381-8_149

[14] Y. Iwahashi, J. Wang, Z. Horita, M. Nemoto, and T.G. Langdon, Principle of Equal-Channel Angular Pressing for the Processing of Ultra-Fine Grained Materials, Scripta Materialia, 35 (1996), 143–146.

DOI: 10.1016/1359-6462(96)00107-8

[15] DIN EN ISO 12004-2, Metallische Werkstoffe – Bleche und Bänder - Bestimmung der Grenzformänderungskurve: Teil 2: Bestimmung von Grenzformänderungskurven im Labor, DIN Deutsches Institut für Normung e.V., 34 pp., (2008).

DOI: 10.31030/3212338

[16] C. Illgen, B. Bohne, M.F.-X. Wagner, M. Gruber, W. Volk, and P. Frint, Facing the Issues of Sheet Metal Equal‐Channel Angular Pressing: A Modified Approach Using Stacks to Produce Ultrafine‐Grained High Ductility AA5083 Sheets, Advanced Engineering Materials, 1 (2021), 2100244.

DOI: 10.1002/adem.202100244

[17] K.W. Gerhardt, Untersuchungen zur konduktiven Erwärmung für Warmzugversuche an Blechen, Dissertation, Shaker Verlag GmbH, (2015).

[18] W. Hotz, M. Merklein, A. Kuppert, H. Friebe, and M. Klein, Time Dependent FLC Determination Comparison of Different Algorithms to Detect the Onset of Unstable Necking before Fracture, Key Engineering Materials, 549 (2013), 397–404.

DOI: 10.4028/www.scientific.net/kem.549.397

[19] M.-A. Kulas, P.W. Green, E.M. Taleff, P.E. Krajewski, and T.R. McNelly, Deformation Mechanisms in Superplastic AA5083 Materials, Metallurgical and Materials Transactions A, 2005, 36A:1249–1261.

DOI: 10.1007/s11661-005-0217-x

[20] R.Z. Valiev, I.V. Alexandrov, Y.T. Zhu, and T.C. Lowe, Paradox of strength and ductility in metals processed by severe plastic deformation, Journal of Materials Research, 17 (2002), 5–8.

DOI: 10.1557/jmr.2002.0002

[21] T. Naka, G. Torikai, R. Hino, and F. Yoshida, The effects of temperature and forming speed on the forming limit doagram for type 5083 aluminum-magnesium alloy sheet, Journal of Materials Processing Technology, 113 (2001), 648–653.

DOI: 10.1016/s0924-0136(01)00650-1

[22] J.D. Bressan, L.P. Moreira, M.C. dos Santos Freitas, S. Bruschi, A. Ghiotti, and F. Michieletto, Modelling of Forming Limit Strains of AA5083 Aluminium Sheets at Room and High Temperatures, Advanced Materials Research, 1135 (2016), 202–217.

DOI: 10.4028/www.scientific.net/amr.1135.202

[23] S. Bruschi, A. Ghiotti, and F. Michieletto, Hot Tensile Behavior of Superplastic and Commercial AA5083 Sheets at High Temperature and Strain Rate, Key Engineering Materials, 554-557 (2013), 63–70.

DOI: 10.4028/www.scientific.net/kem.554-557.63

[24] M.-A. Kulas, P.W. Green, E.M. Taleff, P.E. Krajewski, and T.R. McNelly, Failure mechanisms in superplastic AA5083 materials, Metallurgical and Materials Transactions A, 37 (2006), 645–655.

DOI: 10.1007/s11661-006-0036-8