Detection of Charge Welds in Lateral Angular Co-Extrusion Using Non-Destructive Testing

Abstract:

Although extrusion is a well-established and widely used manufacturing process, charge weld seams remain a persistent challenge due to oxides, contaminants, and unfavorable material flow conditions at billet-to-billet transitions. In lateral angular co-extrusion (LACE), the material flow becomes more complex because it is redirected orthogonally to the ram movement and the metal is segmented into four separate streams in the die. This results in charge weld seams developing in more intricate shapes and locations than in conventional forward extrusion. Knowing the position of these seams along the profile is therefore essential for ensuring the structural integrity of co-extruded hybrid profiles, such as aluminum alloy hollow profiles reinforced by an inner titanium alloy tube. This study investigated the formation of charge weld seams in LACE through controlled billet-on-billet experiments. A hybrid profile was produced consisting of EN AW-6082 aluminum alloy as the lightweight component and a reinforcement element made of titanium grade 5 (Ti-6Al-4V). To enable accurate detection of the charge weld seam within the aluminum alloy part of the profile using non-destructive testing methods, a thin iron foil was inserted as a robust marker prior to extrusion between two parts of a split billet. Eddy-current testing (ET) and ultrasonic testing (UT) were applied to detect and map the charge weld seam along the extruded profile. ET enabled robust, high-resolution circumferential mapping of the weld propagation, while UT provided depth-resolved information. Complementary cross sections were prepared to validate the NDT results and characterize seam morphology. This combined approach provides a clearer picture of the formation of charge weld seams in LACE and demonstrates that NDT techniques can be used to reliably identify and assess these features in complex hybrid profiles.

• Periodical: Key Engineering Materials (Volume 1048)
• Pages: 121-132
• DOI: https://doi.org/10.4028/p-TXaD32
• Online since: April 2026
• Authors: Alexej Verschinin*, Florian Patrick Schäfke, Norman Mohnfeld, Hans Jürgen Maier, Johanna Uhe, Christian Klose, Sebastian Barton
• Keywords: Charge Weld, Lateral Angular Co-Extrusion, Non-Destructive Testing

References

[1] A. Bakker, L. Katgerman, S.d. Zwaag, Analysis of the structure and resulting mechanical properties of aluminum extrusions containing a charge weld interface, Journal of Materials Processing Technology 229 (2016) 9–21.

DOI: 10.1016/j.jmatprotec.2015.09.013

[2] Q. Li, C. Harris, M.R. Jolly, Finite element modelling simulation of transverse welding phenomenon in aluminum extrusion process, Materials & Design 24 (2003) 493–496.

DOI: 10.1016/S0261-3069(03)00123-7

[3] N. Nanninga, C. White, R. Dickson, Charge Weld Effects on High Cycle Fatigue Behavior of a Hollow Extruded AA6082 Profile, Journal of Materials Engineering and Performance 20 (2011) 1235–1241.

DOI: 10.1007/s11665-010-9755-5

[4] J. Yu, G. Zhao, X. Zhao, L. Chen, M. Chen, Microstructures of longitudinal/transverse welds and back-end defects and their influences on the corrosion resistance and mechanical properties of aluminum alloy extrusion profiles, Journal of Materials Processing Technology 267 (2019) 1–16.

DOI: 10.1016/j.jmatprotec.2018.12.006

[5] A.J. den Bakker, R.J. Werkhoven, W.H. Sillekens, L. Katgerman, The origin of weld seam defects related to metal flow in the hot extrusion of aluminum alloys EN AW-6060 and EN AW-6082, Journal of Materials Processing Technology 214 (2014) 2349–2358.

DOI: 10.1016/j.jmatprotec.2014.05.001

[6] L. Donati, L. Tomesani, The prediction of seam welds quality in aluminum extrusion, Journal of Materials Processing Technology 153-154 (2004) 366–373.

DOI: 10.1016/j.jmatprotec.2004.04.215

[7] E.C. Sariyarlioglu, T. Welo, J. Ma, On the mechanisms of charge weld evolution in aluminum extrusion, Journal of Manufacturing Processes 124 (2024) 377–384.

DOI: 10.1016/j.jmapro.2024.06.022

[8] G. Oberhausen, D.R. Cooper, D.R. Cooper, Modeling the Strength of Aluminum Extrusion Transverse Welds Using the Film Theory of Solid-State Welding, 2023.

DOI: 10.1016/j.jmatprotec.2023.118254

[9] A.J. den Bakker, Weld Seams in Aluminum Alloy Extrusions, Delft University of Technology.

[10] M. Engelhardt, D. Behne, N. Grittner, A. Neumann, W. Reimche, C. Klose, Non-destructive Testing of Longitudinal and Charge Weld Seams in Extruded Aluminum and Magnesium Profiles, Materials Today: Proceedings 2 (2015) 4866–4873.

DOI: 10.1016/j.matpr.2015.10.037

[11] X. Zhao, T. Gang, X. Liu, S. Li, Application of ultrasonic non-destructive characterisation on materials' quality evaluation, Insight - Non-Destructive Testing and Condition Monitoring 52 (2010) 206–209.

DOI: 10.1784/insi.2010.52.4.206

[12] J. Krautkrämer, Ultrasonic Testing of Materials, fourth Fully Revised Edition, Springer, Berlin, Heidelberg, 1990.

[13] S.E. Thürer, J. Peddinghaus, N. Heimes, F.C. Bayram, B. Bal, J. Uhe, B.-A. Behrens, H.J. Maier, C. Klose, Lateral Angular Co-Extrusion: Geometrical and Mechanical Properties of Compound Profiles, Metals 10 (2020) 1162.

DOI: 10.3390/met10091162

[14] P. Stucky, W. Lord, Skin Depth Considerations in Eddy Current NDT, in: D.O. Thompson, D.E. Chimenti (Eds.), Review of Progress in Quantitative Nondestructive Evaluation, Springer Science, New York, 1992, p.299–306.

DOI: 10.1007/978-1-4615-3344-3_37

[15] C. Li, C.D. Marioara, C. Hatzoglou, S.J. Andersen, R. Holmestad, Y. Li, Accelerating precipitation hardening by natural aging in a 6082 Al-Mg-Si alloy, Acta Materialia 281 (2024) 120396.

DOI: 10.1016/j.actamat.2024.120396