Direct hot rolling as a solid-state recycling process for green sheets production
Mohamad EL MEHTEDI, Noomane BEN KHALIFA, Pasquale BUONADONNA, Rayane EL MOHTADI, Gianluca MARONGIU, Francesco AYMERICH, Mauro CARTA
Abstract. With the increasing demand for sustainable solutions in the recycling of aluminum alloys, solid-state recycling (SSR) offers an energy-efficient alternative by avoiding the melting phase, which typically leads to high energy consumption and material loss. This study presents a novel SSR process utilizing direct hot rolling to recycle aluminum alloy chips (EN AW-5754). The main objective is to evaluate this process’s feasibility and assess the recycled sheets’ mechanical and microstructural properties. Aluminum alloy chips were produced from the turning process of EN AW-AA5754 bars. The chips were compacted and subsequently heat-treated at 400°C for 2 hours. The compacted samples were then hot rolled in multiple passes, with a final cold rolling step to achieve a final thickness of 0,8 mm. Mechanical properties and microstructure were analyzed using tensile testing machine and SEM-EBSD technique. The recycled samples demonstrated mechanical properties comparable to those of reference material. SEM/EBSD analysis revealed broken oxides and a layered grain structure due to the prior chips’ boundaries. Overall, the results confirm that direct hot rolling can be a viable recycling method for aluminum alloys, offering significant energy and material savings compared to conventional processes.
Keywords
Solid-State Recycling, EN AW-5754, Direct Hot Rolling, Chips, Tensile Tests, EBSD
Published online 5/7/2025, 10 pages
Copyright © 2025 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Mohamad EL MEHTEDI, Noomane BEN KHALIFA, Pasquale BUONADONNA, Rayane EL MOHTADI, Gianluca MARONGIU, Francesco AYMERICH, Mauro CARTA, Direct hot rolling as a solid-state recycling process for green sheets production, Materials Research Proceedings, Vol. 54, pp 1459-1468, 2025
DOI: https://doi.org/10.21741/9781644903599-158
The article was published as article 158 of the book Material Forming
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
References
[1] D. Raabe, D. Ponge, P.J. Uggowitzer, M. Roscher, M. Paolantonio, C. Liu, H. Antrekowitsch, E. Kozeschnik, D. Seidmann, B. Gault, F. De Geuser, A. Deschamps, C. Hutchinson, C. Liu, Z. Li, P. Prangnell, J. Robson, P. Shanthraj, S. Vakili, C. Sinclair, L. Bourgeois, S. Pogatscher, Making sustainable aluminum by recycling scrap: The science of “dirty” alloys, Progress in Materials Science 128 (2022) 100947. https://doi.org/10.1016/j.pmatsci.2022.100947
[2] S. Shamsudin, M. Lajis, Z. Zhong, Solid-state recycling of light metals: A review, Advances in Mechanical Engineering 8 (2016) 168781401666192. https://doi.org/10.1177/1687814016661921
[3] B. Wan, W. Chen, T. Lu, F. Liu, Z. Jiang, M. Mao, Review of solid state recycling of aluminum chips, Resources, Conservation and Recycling 125 (2017) 37-47. https://doi.org/10.1016/j.resconrec.2017.06.004
[4] J. Gronostajski, H. Marciniak, A. Matuszak, New methods of aluminium and aluminium-alloy chips recycling, Journal of Materials Processing Technology 106 (2000) 34-39. https://doi.org/10.1016/S0924-0136(00)00634-8
[5] J.Z. Gronostajski, J.W. Kaczmar, H. Marciniak, A. Matuszak, Direct recycling of aluminium chips into extruded products, Journal of Materials Processing Technology 64 (1997) 149-156. https://doi.org/10.1016/S0924-0136(96)02563-0
[6] A.E. Tekkaya, M. Schikorra, D. Becker, D. Biermann, N. Hammer, K. Pantke, Hot profile extrusion of AA-6060 aluminum chips, Journal of Materials Processing Technology 209 (2009) 3343-3350. https://doi.org/10.1016/j.jmatprotec.2008.07.047
[7] K. Xia, X. Wu, Back pressure equal channel angular consolidation of pure Al particles, Scripta Materialia 53 (2005) 1225-1229. https://doi.org/10.1016/j.scriptamat.2005.08.012
[8] L. Hendriok, M. Nienaber, G. Kurz, N. Ben Khalifa, Die geometry influence on the texture and microstructure development during extrusion of AZ31 and ZK60 magnesium alloy chips, Materials & Design 249 (2025) 113545. https://doi.org/10.1016/j.matdes.2024.113545
[9] W. Tang, A.P. Reynolds, Production of wire via friction extrusion of aluminum alloy machining chips, Journal of Materials Processing Technology 210 (2010) 2231-2237. https://doi.org/10.1016/j.jmatprotec.2010.08.010
[10] M. El Mehtedi, A. Forcellese, T. Mancia, M. Simoncini, S. Spigarelli, A new sustainable direct solid state recycling of AA1090 aluminum alloy chips by means of friction stir back extrusion process, Procedia CIRP 79 (2019) 638-643. https://doi.org/10.1016/j.procir.2019.02.062
[11] F. Abu-Farha, A preliminary study on the feasibility of friction stir back extrusion, Scripta Materialia 66 (2012) 615-618. https://doi.org/10.1016/j.scriptamat.2012.01.059
[12] S. Bocchi, M. Negozio, C. Giardini, L. Donati, Prediction of the microstructure evolution during the friction stir extrusion of a AA6061 aluminum alloy, (2024) 678-687. https://doi.org/10.21741/9781644903131-75
[13] M. Carta, P. Buonadonna, M. El Mehtedi, Numerical Analysis of Process Parameters and Tool Geometry in Friction Stir Back Extrusion of Pure Aluminum, Procedia CIRP 126 (2024) 710-714. https://doi.org/10.1016/j.procir.2024.08.294
[14] M.I. Abd El Aal, E. Yoo Yoon, H. Seop Kim, Recycling of AlSi8Cu3 alloy chips via high pressure torsion, Materials Science and Engineering: A 560 (2013) 121-128. https://doi.org/10.1016/j.msea.2012.09.045
[15] S. Goussous, W. Xu, X. Wu, K. Xia, Al-C nanocomposites consolidated by back pressure equal channel angular pressing, Composites Science and Technology 69 (2009) 1997-2001. https://doi.org/10.1016/j.compscitech.2009.05.004
[16] D. Baffari, G. Buffa, D. Campanella, L. Fratini, Al-SiC Metal Matrix Composite production through Friction Stir Extrusion of aluminum chips, Procedia Engineering 207 (2017) 419-424. https://doi.org/10.1016/j.proeng.2017.10.798
[17] K. Suzuki, X.S. Huang, A. Watazu, I. Shigematsu, N. Saito, Recycling of 6061 Aluminum Alloy Cutting Chips Using Hot Extrusion and Hot Rolling, MSF 544-545 (2007) 443-446. https://doi.org/10.4028/www.scientific.net/MSF.544-545.443
[18] R. Chiba, T. Nakamura, M. Kuroda, Solid-state recycling of aluminium alloy swarf through cold profile extrusion and cold rolling, Journal of Materials Processing Technology 211 (2011) 1878-1887. https://doi.org/10.1016/j.jmatprotec.2011.06.010
[19] J.M. Allwood, Y. Huang, C.Y. Barlow, Recycling scrap aluminium by cold-bonding, (2005)
[20] M. El Mehtedi, P. Buonadonna, M. Carta, R. El Mohtadi, A. Mele, D. Morea, Sustainability Study of a New Solid-State Aluminum Chips Recycling Process: A Life Cycle Assessment Approach, 15 (2023) 11434. https://doi.org/10.3390/su151411434
[21] M. Carta, N. Ben Khalifa, P. Buonadonna, R. El Mohtadi, F. Bertolino, M. El Mehtedi, Innovative Solid-State Recycling of Aluminum Alloy AA6063 Chips Through Direct Hot Rolling Process, Metals 14 (2024) 1442. https://doi.org/10.3390/met14121442
[22] M. Carta, N. Ben Khalifa, P. Buonadonna, A. Mele, M. El Mehtedi, Life cycle assessment (LCA) of a novel solid-state recycling process for aluminum alloy AA6063 chips via direct hot rolling, (2024) 2881-2890. https://doi.org/10.21741/9781644903131-315
[23] M. El Mehtedi, P. Buonadonna, R. El Mohtadi, G. Loi, F. Aymerich, N. Ben Khalifa, M. Carta, Feasibility Study of Solid-State Recycling through Direct Hot Rolling of AA5754 Aluminum Chips for Automotive Applications, MSF 1130 (2024) 3-12. https://doi.org/10.4028/p-J0bRTh
[24] Y.J. Chen, Y.C. Chai, H.J. Roven, S.S. Gireesh, Y.D. Yu, J. Hjelen, Microstructure and mechanical properties of Al-xMg alloys processed by room temperature ECAP, Materials Science and Engineering: A 545 (2012) 139-147. https://doi.org/10.1016/j.msea.2012.03.012
[25] R. Kalsar, D. Yadav, A. Sharma, H.-G. Brokmeier, J. May, H.W. Höppel, W. Skrotzki, S. Suwas, Effect of Mg content on microstructure, texture and strength of severely equal channel angular pressed aluminium-magnesium alloys, Materials Science and Engineering: A 797 (2020) 140088. https://doi.org/10.1016/j.msea.2020.140088
[26] N.C.W. Kuijpers, F.J. Vermolen, C. Vuik, P.T.G. Koenis, K.E. Nilsen, S.V.D. Zwaag, The dependence of the β-AlFeSi to α-Al(FeMn)Si transformation kinetics in Al-Mg-Si alloys on the alloying elements, Materials Science and Engineering: A 394 (2005) 9-19. https://doi.org/10.1016/j.msea.2004.09.073
[27] Z. Zhang, J. Liang, T. Xia, Y. Xie, S.L.I. Chan, J. Wang, D. Zhang, Effects of Oxide Fragments on Microstructure and Mechanical Properties of AA6061 Aluminum Alloy Tube Fabricated by Thermomechanical Consolidation of Machining Chips, Materials 16 (2023) 1384. https://doi.org/10.3390/ma16041384
[28] M. Laurent-Brocq, L. Lilensten, C. Pinot, A. Schulze, A. Duchaussoy, J. Bourgon, E. Leroy, A.E. Tekkaya, Solid state recycling of aluminium chips: multi-technique characterization and analysis of oxidation, Materialia (2023) 101864. https://doi.org/10.1016/j.mtla.2023.101864
[29] Y. Chino, T. Hoshika, J.-S. Lee, M. Mabuchi, Mechanical properties of AZ31 Mg alloy recycled by severe deformation, J. Mater. Res. 21 (2006) 754-760. https://doi.org/10.1557/jmr.2006.0090
[30] H. Halim, D.S. Wilkinson, M. Niewczas, The Portevin-Le Chatelier (PLC) effect and shear band formation in an AA5754 alloy, Acta Materialia 55 (2007) 4151-4160. https://doi.org/10.1016/j.actamat.2007.03.007
[31] Aluminium Alloy – Commercial Alloy – 5754 – H26 Sheet. Information on https://www.aalco.co.uk/datasheets/Aluminium-Alloy-5754-H26-Sheet_341.ashx,
[32] R. Yakut, N. Ürkmez Taşkın, Production of AA5754/B4C composite materials by the semi-solid stirring method, NWSA 14 (2019) 57-67. https://doi.org/10.12739/NWSA.2019.14.2.2A0169
