Ural Federal University named after the First President of Russia B. N. Yeltsin, Yekaterinburg, Russia¹ ; Mikheev Institute of Metal Physics at the Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia²

Yu. N. Loginov, Professor at the Department of Metal Forming¹, Doctor of Technical Sciences, Lead Researcher², e-mail: j.n.loginov@urfu.ru

Kamensk-Uralsky Metallurgical Works OJSC, Kamensk-Uralsky, Russia
A. V. Razinkin, Process Director, Candidate of Technical Sciences, e-mail: RazinkinAV@kumz.ru

Ural Federal University named after the First President of Russia B. N. Yeltsin, Yekaterinburg, Russia
G. V. Shimov, Associate Professor at the Department of Metal Forming, Candidate of Technical Sciences, e-mail: g.v.shimov@urfu.ru
N. I. Bushueva, Research Engineer at the Metal Forming Research Laboratory, e-mail: n.i.bushueva@urfu.ru

This paper considers the process of extrusion of aluminium alloy 6061 bars aimed at finding a way to minimize the in-process metal loss due to the use of an additional work piece (in the form of back plug) made of cheaper material. Numerical modelling of the extrusion process was carried out for three different heating modes applied to both the tooling and the work pieces. The authors analyzed the mutual flow of the ingot and plug material at the final stage of extrusion in order to determine the moment when the back end defect starts to form and how it forms. The stress-strain state for three process options was investigated. Thus, the authors looked at the colour gradient pictures showing the distribution of strain and strain rate longitudinally along the extrusion centerline. It was found that when a pre-heated additional work piece is used, the butt-end should be made larger because of the early formed back end defect. When a cold plug and a hot dummy block are used, the back end defect forms early as well, as the back plug heats up at the final process stage reaching almost the same temperatures as the main work piece. It was established that the optimum option would be not heating the back work piece or the dummy block. The modelling helped reveal that the size of the buttend in this case is smaller. The obtained modelling data can be used for conducting pilot studies aimed at reducing the size of the butt-end when producing extruded aluminium bars. This will help improve the metal utilization factor.
This research was carried out as part of Project No. 22-29-00931 dated 20/12/2021 by the Russian Science Foundation.

1. Namburi K.-P. V., Kothasiri A. F., Yerubandi V.-S. M. Modeling and simulation of Aluminum 1100 alloy in an extrusion process. Materials Today: Proceedings. 2020. Vol. 23, Iss. 3. pp. 518–522. DOI: 10.1016/j.matpr.2019.05.398
2. Vydrin A. V., Zhukov A. S., Tumashev A. S., Zvonarev D. Yu. et al. Relationship between the die profile and the nature of stress-strain state in pipe extrusion. Vestnik Yuzhno-Uralskogo gosudarstvennogo universiteta. Seriya: Metallurgiya. 2021. Vol. 21, No. 3. pp. 49–55.
3. Loginov Yu. N., Antonenko L. V. On strain rate conditions in the container during direct extrusion. Tekhnologiya legkikh splavov. 2010. No. 4. pp. 66–72.
4. Chanda T., Zhou J., Duszczyk J. FEM analysis of aluminium extrusion through square and round dies. Materials & Design. 2000. Vol. 21, Iss. 4. pp. 323–335. DOI: 10.1016/S0261-3069(99)00073-4
5. Loginov Yu. N., Semenov A. P. Changing tool temperature during hot extrusion of copper and brass bars. Forging and Stamping Production. Material Working by Pressure. 2006. No. 4. pp. 10–13.
6. Yadav R. R., Raghuwanshi Y.-D. J., Sharma V. Finite element analysis of extrusion process using aluminum alloy. Materials Today: Proceedings. 2020. Vol. 24, Iss. 2. pp. 500–509. DOI: 10.1016/j.matpr.2020.04.302
7. Khadyko M., Morin D., Børvik T., Hopperstad O. S. Tensile ductility of extruded aluminium alloy AA6063 in different tempers. Materials Science and Engineering: A. 2019. Vol. 744. pp. 500–511. DOI: 10.1016/j.msea.2018.12.048
8. Kawalek A., Bajor T., Kwapisz M., Sawicki S. et al. Numerical modeling of the extrusion process of aluminum alloy 6XXX series section. Journal of Chemical Technology & Metallurgy. 2021. Vol. 56, No. 2. pp. 375–381.
9. Herba E. M., McQueen H. J. Influence of particulate reinforcements on 6061 materials in extrusion modeling. Materials Science and Engineering: A. 2004. Vol. 372, Iss. 1-2. DOI: 10.1016/j.msea.2003.08.006
10. Dmitryuk A. I., Grigoriev A. A. Optimized aluminium extrusion process. Zagotovitelnye proizvodstva v mashinostroenii. 2020. Vol. 18, No. 8. pp. 353–358.
11. Deryabin A. Yu., Kargin V. R. Modelling the final stage of extrusion of large bars at low extrusion degrees at the moment of central back end defect forming. Izvestiya Samarskogo nauchnogo tsentra Rossiyskoy Akademii Nauk. 2018. Vol. 20, No. 1(81). pp. 5–10.
12. Loginov Yu. N., Ershov A. A. Use of QFORM for modelling of extrusion defect forming. Forging and Stamping Production. Material Working by Pressure. 2013. No. 7. pp. 42–46.
13. Hatzenbichler T., Buchmayr B., Umgeher A. A numerical sensitivity study to determine the main influence parameters on the back-end defect. Journal of Materials Processing Technology. 2007. Vol. 182, Iss. 1-3. pp. 73–78. DOI: 10.1016/j.jmatprotec.2006.07.013
14. Dmitriev A. I., Kalenov S. V., Urin S. L., Gubina N. A. Understanding the reason for high rejection rate when extruding 500 kg ingots. Ferrous Metallurgy. Bulletin of Scientific, Technical and Economical Information. 2012. No. 8(1352). pp. 48–51.
15. Balasundar I., Raghu T. Investigations on the extrusion defect — Axial hole or funnel. Materials and Design. 2010. Vol. 31, Iss. 6. pp. 2994–3001. DOI: 10.1016/j.matdes.2010.01.027
16. Liu C. H., Yang J. B., Lin H. C. Design of a novel dummy block by finite element simulation to eliminate back end defects in direct extrusion. Transactions of the Indian Institute of Metals. 2016. Vol. 69. pp. 1699–1710. DOI: 10.1007/s12666-016-0830-y