Modelling towards Value-added Recycling Friendly Aluminium Alloys

In collaboration with two industrial partners, Hydro Aluminium and Sapa Technology (now Graenges AB), SINTEF and NTNU has carried out a 5 years KPN project, entitled as Modelling towards value-added recycling friendly aluminium alloys (MOREAL). The main objective of the MOREAl project has been to contribute to resolving those challenges related to recycled aluminium alloys through improved understanding and quantitative description of the influence of different alloying elements on microstructure, processing properties and mechanical properties of the alloys, with a special attention to alloys containing Mn, Fe and Si, which typically accumulate during recycling. Another main objective has been is to develop and implement numerical models that predict the influence of the variation of chemical compositions and the increased level of impurities. After 5 years of research work, all main objectives and milestones the milestones have been achieved, in accordance with the original research plan. An in-depth understanding of the influence of different alloying elements on the solidification structure, the evolution of chemistry and phase changes during heat treatment, the deformation ability and the mechanical properties of the final product has been established. Three computer simulation models have been developed, which can predict the evolution of the microstructure, chemistry and the deformation behavior during different thermo mechanical processes. New experimental techniques and modeling methodologies have been obtained in the project, for example the 3D-tomography technology in transmission electron microscopy and different atomic scale modeling techniques. The project work has so far resulted in 29 papers in refereed international journals, 5 PhD theses (3 in Moreal, 2 in associated projects), 41 oral and poster presentations atin international conferences and seminars, 1 popular science articles and 60 oral presentations in project meetings. Another 5-10 papers based on results from the work of the Ph.Ds, postdocs and researchers, are under preparation or planned for publication in international journals during 2015. The project has altogether educated 5 Ph.D and 2 postdocs and 3 of them now have been employed by the two industrial partners. In the last years internal R&D activities have been carried out in the two companies in parallel to the project. Both of the industrial partners are satisfied with the project results. Hydro is utilising the project results in design of new alloys for various applications such as beverage cans, heat transfer/air-conditioning systems, lithographic sheets, foil etc. Hydro is also using the models developed in the project on a daily basis optimising internal processes as well as in discussions/collaboration with customers in different market areas. Granges has started to use the competence developed to optimize their heat treatment processes, measure the particle size and distribution and to control the textures in their products.

The long term vision of the Norwegian aluminium industry is to be world leading with respect to sustainability and competitiveness. However, the fast growing energy cost and increasingly strict environmental regulations have gradually driven the primary a luminium production out of Europe. The European aluminium industry is also facing a strong competition from the emerging economies. In order to meet these challenges and realise a sustainable development, Norwegian aluminium industry must provide the best quality products at a competitive price of both primary-based and recycle-based aluminium. An increased use of recycled aluminium requires the development of new tailor made alloys and an optimisation of the thermo mechanical processing routes so that t o handle the corresponding changes and variations of chemical compositions (alloying elements and impurities). However, to meet this challenge, the traditional plant trials are both costly and time-consuming. To survive these critical circumstances requir es the activation of long term and more fundamental academic science support for significantly better and more intelligent alloy design and material processing strategies. Advanced mathematical modelling tools, as a complementation to traditional experime ntal research, are believed to be a powerful tool to meet the challenges. The objective of the present project is to develop state-of-the-art, physically based numerical through process models to predict the microstructure evolution during homogenisation, deformation, and softening (recovery and recrystallization) as well as the mechanical properties of the semi products of primary and recycle-based aluminium alloys. The model development will be based on a comprehensive and detailed experimental characte rization of the roles of alloying elements and impurities in various processing steps and their specific influences on the properties during processing and in the semi-finished state.