Aluminium alloys for minimizing CO2 emissions

New research by TRIMET provides evidence that trimal-38 can absorb a higher proportion of recycled material with iron and copper components without compromising its mechanical properties. This means the alloy enables a further reduction of the CO₂ footprint. Using recycled aluminium instead of primary metal can save up to 85% of CO₂ emissions and 95% of the energy required. TRIMET has already made use of this effect for the alloy trimal-04 (AlSi10MnMg). Vehicle manufacturers and other users are successfully using this recycled alloy as an alternative to the primary alloy trimal-05 (AlSi10MnMg).

“SUPA-Wheel” research project

TRIMET is contributing its materials development expertise to the “SUPA-Wheel” research project. The aim of the joint project from Dortmund University of Applied Sciences and Arts is to develop an aluminium wheel that meets the technical, economic and ecological requirements of manufacturers for different drivetrains. Project participants are working on a cross-industry and cross-material development and design methodology that calculates the CO₂ balance of a product and then takes it into account during processing. The objective is to reduce CO₂ emissions and even avoid them altogether where possible.

In the project, TRIMET has been tasked with developing, characterizing and producing recyclable materials and those derived from recycled sources for wheel production via the low-pressure casting method. Equilibrium, microstructure and property simulations, laboratory castings and specific heat treatments are evaluated using a development methodology based on the design of experiment (DoE) technique. By conducting a subsequent property screening, it becomes feasible to progressively approach the alloy that best fulfills the specified requirements through an iterative process.

In characterizing and evaluating the laboratory materials, TRIMET is primarily pursuing the goal of using the highest possible proportion of recycled aluminium. In addition to suitable pre-treatment and cleaning measures for the recycling material, the various development alloys are melted and the maximum possible proportion of recycled material is determined. In addition, TRIMET specialists are investigating alloying techniques in order to attain the required property profile as cost-effectively as possible. The company produces the most promising alloys on a pre-series and production scale in its testing facilities. The project partners then process these alloys on the appropriate scale using low-pressure die casting.

With this sub-project, TRIMET is pursuing the goal of gaining a fundamental understanding of the relevant interactions between process parameters and their effects on the technological properties of secondary materials along the entire process chain. In addition to TRIMET, the companies Borbet and Jordan Spritzgusstechnik, along with the Fraunhofer IGCV Research Institute, are the partners involved in “SUPA-Wheel”. The project, which will run until the end of 2025, is being funded by the German Federal Ministry for Economic Affairs and Climate Protection with resources from the Lightweight Construction Technology Transfer Program.

Alloys with a high level of recycled content

When it comes to materials that meet sustainability requirements, TRIMET has extensive experience. For example, the company’s Research and Development department develops recyclable alloy variants of commercially available primary alloys. This ensures that the new alloys maintain properties that are not significantly different from their primary metal counterparts. This applies across sectors to structural components and frames used in machine engineering, window and door profiles in the construction sector, conductors in the energy industry, structural components used in wind power and photovoltaic plants, as well as bumpers and battery boxes in vehicle manufacturing. Examples of sustainable material alternatives are the wrought alloys trimal-52 and trimal-53, which combine maximum strength and corrosion resistance with the crash suitability required for use in structural components.

In addition to standard materials, the company develops special alloys for specific applications in close cooperation with its customers. The latest computer-aided simulation technology is available for this purpose, including the CALPHAD method and a casting/solidification simulation based on the finite element method, as well as laboratory equipment enabling mechanical tests, microstructure investigations (Opt.-mic., SEM, XRD) and the determination of electrical and chemical corrosion properties. In addition, there are several miniature smelting and heat treatment units for formats from five to 40 kilograms, as well as a test casting facility on a near-production scale. This enables TRIMET to cast special alloys in trial quantities of up to five tons in exactly the same geometries that processors use under real conditions in their production systems.