ALLEGRO – High-performance components made of aluminium alloys through resource-optimized process technologies

The core objective of Allegro is to create a technology base for new efficient processes of integrated shaping and heat treatment of the high strength AA7075 aluminum alloy. The technology development should be accelerated and transferred into the application by a synergistic combination of the relevant technology building blocks (forming, tribology, joining, coating, material characterization, component properties and service life). At PtU, a roll forming process is investigated using temperature-supported process routes. On the one hand, the temperature support favors the formability of the high-strength aluminum alloy AA7075. On the other hand, improved and tailored mechanical properties of the roll-formed profiles are an outcome.

Coordinator: Timon Suckow M. Sc.
Duration: January 2018 – June 2022
Funded by: LOEWE-Förderlinie 3

Motivation

Current research in production technology focuses on the increase of resource-efficiency and follow the approach of a fundamental sustainability of products and processes. Resource-efficiency refers to the entire lifecycle of the product, including the use of energy and other resources up to the point of reintroduction into the material cycle. In the area of aluminum forming, there is a great improvement potential to achieve higher resource efficiency. In contrast to the current production where time-consuming and expensive subsequent heat treatments are necessary, a process-integrated realization of the target properties is to be achieved through novel process chains. Components with graded properties through targeted heat treatment which enable an excellent lightweight construction potential may serve as an example. In the electric mobility sector in particular, sustainable lightweight construction is required, as there are limited energy storage capacities.

[1] Process chain for the production of a high-strength aluminum tube

Approach

In addition to PtU, the Institute of Materials Science and the Fraunhofer Institute for Structural Durability and System Reliability in Darmstadt are involved in the overall ALLEGRO project, furthermore two institutes of the University of Kassel. These include the Institute of Materials Science / Metallic Materials and the Institute of Cutting and Joining Manufacturing Processes.

Additionally, a number of SME joint projects are technically integrated into the Allegro project at PtU.

  • 2018 – 2019: WarmAp (hot forming of aluminum sheets for high-performance components of future mobility concepts)
  • 2020 – 2021: RAmP (Load optimized sheet metal components made of high-strength aluminium)
  • 2022 – 2023: PrositAl dual (Productivity assurance of temperature-supported aluminum forming processes through dual research and education)

The objectives of the SME joint projects are the implementation and testing of the technological advances made in Allegro in an industry-related environment and the development of new product groups with a significant increase in the complexity of the components. The partners for process implementation and method planning are Werner Schmid GmbH (multi-stage deep drawing) and Hörmann Automotive Gustavsburg GmbH (deep drawing with local heating). Filzek TRIBOtech GmbH as an expert in tribological issues completes the co-operating partners list.

In addition to the SME joint projects, the focus of the investigations at PtU is on roll forming and press hardening of high-strength aluminum profiles. The challenges of poor formability and weldability are addressed in a process chain for roll forming a tube made from the high-strength aluminum alloy AA7075. Figure 1 illustrates the process chain.

A resource-optimized execution of the process chain shown in the figure does not include heating and quenching systems. Due to the incremental character of roll forming, even high-strength materials can be formed. The challenge in roll forming a high-strength aluminum tube is the high springback during forming [1]. This leads to problems during welding due to high restoring forces of the tube and thus high residual stresses. Lower springback can be achieved by temperature-supported process routes, as shown in Figure 1. Inductive inline heating of the sheet up to solution annealing temperature of T = 460 °C – 480 °C and subsequent quenching brings the material into the W-temper condition. This results in an improvement of the formability and thus to an extension of the process limits, even for cold forming. This process route can also be applied to produce profiles with small bending radii (e.g. U- or hat-profiles).

Another option for inline heat treatment is heat treatment after forming and welding. This leads to an increase of weld strength by up to 50 %, even for very short solution annealing times from 10 s – 30 s [2]. On the other hand, tailored properties for the tube or profile can be set which enables the production of load-optimized profiles and tubes.

Project related publications

Groche, Peter; Günzel, Janosch; Suckow, Timon (2018):
Blechkomponenten aus hochfestem Aluminium – Möglichkeiten und Potenzial der Inline-Wärmebehandlung von EN AW-7075 beim Walzprofilieren.
In: wt Werkstattstechnik online, 10 (108), S. 639-645, Springer-VDI-Verlag, [Artikel]

Suckow, Timon; Günzel, Janosch; Schell, Lukas; Sellner, Erik; Dagnew, Jonathan; Groche, Peter (2019):
Temperatureinfluss in der Aluminium-Blechumformung – Rückfederungsverhalten und Prozessgrenzen beim Gesenkbiegen von EN AW-6082 und EN AW-7075.
In: wt Werkstattstechnik online, 10 (109), S. 733-739, VDI Fachmedien, [Artikel]

Günzel, Janosch; Suckow, Timon; Veitenheimer, Ciaran; Hauß, Joachim; Groche, Peter (2020):
Robuste W-Temper-Umformung von hochfestem Aluminium = Robust W-Temper forming of high-strength aluminum : how time and quenching method affect the mechanical properties of EN AW-7075.
In: Werkstattstechnik online: wt, 10 (110), S. 697-703, VDI Fachmedien, ISSN: 1436-5006, DOI: 10.37544/1436-4980-2020-10-53, [Artikel]

Suckow, Timon; Schroeder, Julius; Groche, Peter (2021):
Roll forming of a high strength AA7075 aluminum tube.
In: Production Engineering, S. 573-586, Springer, ISSN: 0944-6524,
DOI: https://doi.org/10.1007/s11740-021-01046-2, [Artikel]

Günzel, Janosch; Suckow, Timon; Sellner, Erik; Schell, Lukas; Fawaro, Andreas; Groche, Peter (2021):
Effizienter Leichtbau durch moderne Prozesstechnologien.
In: Technik und Mensch, 2 (2021), S. 11-13, VDI, ISSN: 1611-5546, Offizielle URL, [Artikel]

Suckow, Timon; Groche, Peter (2021):
Effiziente Umformung hochfester Aluminiumlegierungen am Beispiel des Rollformens.
In: VDI Technik und Mensch, 3, S. 6, [Artikel]

Suckow, Timon; Völkers, Stephan; Bütev Öcal, Ezgi; Grass, Markus; Böhm, Stefan; Groche, Peter (2022):
Effect of Shortened Post Weld Heat Treatment on the Laser Welded AA7075 Alloy.
In: metals, 12(3), 393. DOI: https://doi.org/10.3390/met12030393, [Artikel]

Acknowledgement

The Institute for Production Engineering and Forming Machines would like to thank LOEWE, the Hessen Agency and the partners involved for their support in the implementation of this project.

Funded by

Project Partners