CD Laboratory for Inclusion Metallurgy in Advanced Steelmaking

Climate change, digitalization, and globalization leads to the necessity of adapting the steel production route. The research of this CD Laboratory focuses on non-metallic inclusions (NMIs), studying their formation and properties in different steel production processes.

The sometimes very high requirements on steels in various applications, as well as the competition with other materials, lead to increasing demands on steel quality. Despite the long history of steel production and the continuous product development through innovative plant and process engineering solutions, steel manufacturers today continue to face the challenge of sustainably improving both products and processes.

The formation of so-called non-metallic inclusions is unavoidable during steel production. NMIs are particles with different properties compared to the surrounding steel matrix, which is why they generally affect the final material properties negatively. In contrast, under certain conditions, inclusions can also act as nucleation sites for certain microstructures and thus have a positive effect on the material properties. The major current challenge is to further improve the already very high cleanness of steels in many areas and to adapt secondary metallurgy to the new issues arising from alternative methods of crude steel production.

The research field of inclusion metallurgy deals with various aspects of the formation, modification, dissolution and characterization of NMIs in different process stages. The overarching idea of this CD Laboratory is to cover the process from the formation of NMIs through the modification in the steel, slag or refractory material, as well as at the respective interfaces, to the effect on the product properties. Due to comparable basic mechanisms and reactions, powder metallurgy for the production of high-alloyed tool steels will also be examined in addition to steels for the automotive industry. One focus is the further development of methods for inclusion analysis using machine learning and the representative analysis of inclusions in the meso size range, i.e., with an equivalent circle diameter between 15 and 100 µm. Furthermore, selected aspects of interfacial properties and reactions of NMIs will be analyzed. Special attention will be paid to the role of alkali elements and rare earths in influencing the modification of inclusions.

In addition to industrial trials, specific inclusion populations are investigated in the laboratory; high-temperature laser scanning confocal microscopy and drop shape analyses are essential methods for determining the NMI behavior. A new approach for inclusion tracking over the manufacturing process will be tested by using natural and enriched stable isotopes.