Holistic sustainability of metals and alloys value chains

Researcher: Ida Kero

Steel is one of the most recycled commodities in the world. However, most of what we call recycling today is downcycling. It means that the recycled products are significantly poorer in quality than the original products. As an example, it is not possible to make new cars out of old, scrapped cars. The quality of the steel would not be good enough. The main goal of this project is to identify and develop methods to avoid downcycling and minimize the dependence on primary (ore based) iron.

In the short term, improved recycling may for example come from innovations with respect to dismantling old products, information sharing across value chains and networks to enable optimization, as well as sorting and characterization of scrap so that every steel class can be recycled as itself in so-called alloy-to-alloy recycling.

In a longer perspective, the strategies should aim to reduce the diversity and complexity of steel alloys (grades) in use and in production, so that fewer elements need to be added in the first place. It may be possible to decrease the number of alloying elements in steel, as well as their concentration, by improved control of the steel microstructures by uniquely optimized thermomechanical processing. The idea of producing many different grades by differentiated processing of the same chemical composition is sometimes referred to as the unialloy approach. This would require new alloy design methods which focus on the microstructure rather than chemical composition.

This project is a collaboration between LTU and the Wallenberg Initiative Materials Science for Sustainability (WISE), funded by the Knut and Alice Wallenberg Foundation. WISE is the largest investment in materials science ever made in Sweden and includes major investments at the leading universities in Sweden. The vision is a sustainable future through materials science. Read more at: https://wise-materials.org/.

Sustainability aspects

The iron and steel industry is important to society for many different reasons. It is a major driver of economic growth and employs 6 million people worldwide. Hence, the steel industry is key to our welfare. The steel products themselves are necessary to uphold our current quality of life, and they are required for the development of poorer countries and communities. Steel is also needed in weatherproof buildings, bridges, etc. and therefore necessary for climate adaptation.

Other societal and financial motivations for improving recycling, avoiding downcycling and reducing the reliance on iron ores are the improved resilience and reduced supply chain risks. Additionally, it would enable us to retain and make use of the critical and strategic raw materials that are often included in steel as alloying elements.