NextBillet - Next generation billets for structural aluminium extrusions

As the world moves toward carbon neutrality and circular economy, the recyclability of lightweight aluminium alloys becomes a key advantage. Recycling aluminium requires only 5% of the energy needed for primary production, saving energy, natural resources and significantly decreasing the CO2 footprint. However, producing large, defect-free, high-quality billets from recycled alloys remain a significant technical challenge. The NextBillet project addresses this challenge by advancing low-pressure direct-chill casting (LPC) through the integration of physics-based models and real-time, data-driven control systems. Recycled aluminium often contains impurity elements like iron, silicon, zirconium and zinc, which can undermine the solidification process. To understand their impact, the project combines dedicated laboratory experiments with advanced solidification simulations to study how varying impurity concentrations influence grain structure, crack susceptibility, and surface quality in the as-cast billets. In parallel, the project deploys advanced sensor arrays to monitor temperature, pressure, and coolant flow within industrial moulds. These data streams feed into machine-learning algorithms trained to detect early signs of casting defects—such as hot spots, gas entrapment, or uneven solidification—and dynamically adjust process parameters. This adaptive control expands the LPC process window, enabling existing extrusion lines to successfully handle recycled aluminium with fluctuating compositions. NextBillet aims to produce high-quality billets from recycled stock, suitable for extruding wide beams, turbine towers, and bridge girders—without the need for ultra-high-tonnage presses or blending with primary aluminium. By combining advanced materials science with agile, data-driven process control, NextBillet will transform recycled aluminium into a high-performance resource—laying the foundation for a circular aluminium economy and a more sustainable environment.

Aluminium as a future material will play an important role in accelerating the green transition. Aluminium is highly recyclable, and recycling consumes only 5% of the energy required to produce the same amount of primary aluminium. This makes recycled aluminium attractive for various applications, and there are increasingly demands for including recycled aluminium in products especially large extrusions to be used in automotive, renewable energy and bridges. However, there is a strict requirement of billet quality in terms of homogeneous microstructure and surface quality to fabricate those large extruded profiles. This becomes more critical when increasing amount of recycled aluminium are used. NextBillet project aims to develop next generation LPC technology combined with physic-based models and data-driven methods to produce superior billets with recycled aluminium, enabling resource-efficient extrusions. The R&D challenges include: 1) understanding the effects of accumulating impurity elements from recycling on grain inoculation and solute poisoning 2) increased knowledge on the relation between composition, castability and process parameters and developing physics-based models and 3) developing data-driven casting process optimization for minimal cast defects. In reference to the current LPC system, the new system will have a considerably wider operational window that can handle the variations of chemical composition inherent with using recycled aluminium while maintaining higher billet quality. The current system will be improved by implementing physics-based data-driven control strategies to increase its adaptivity and flexibility. It will also be demonstrated the high quality billets enable the resource-efficient extrusions of large, wide extrusion profiles with the existing extrusion equipments available in Norway. NextBillet project will be a collaboration between Hydro Aluminium AS, Hycast AS, Sintef AS and Brunel University.