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MM: Fachverband Metall- und Materialphysik

MM 7: Mechanical Properties and Alloy Design II

MM 7.8: Talk

Monday, March 9, 2026, 17:45–18:00, SCH/A215

Understanding the influence of residual elements on the toughness of martensitic steels towards recycled steels — •Eloho Okotete, Subin Lee, and Christoph Kirchlechner — Karlsruhe Institute of Technology, Karlsruhe, Germany

Martensitic steels are critical for many load-bearing applications due to their inherent microstructure, giving rise to unique mechanical properties. However, traditional steelmaking routes produce high greenhouse gas emissions, posing a long-term threat to our environment. Cleaner steel production alternatives aim to use recycled iron scrap as input to electric arc furnaces used in steelmaking. A significant concern for key stakeholders in the steel industry and academia is the presence of residual elements, including Cu, Sn, Sb, As, and P, in iron scrap. Hence, an in-depth analysis of the role of the residual elements on the local and global mechanical properties of martensitic steel would provide relevant insights for the development of environmentally friendly steelmaking alternatives. Small-scale mechanics using indentation-based techniques can help locally probe how the critical microstructural features of lath martensite, such as prior austenite grain boundaries, packets, blocks, and laths, are affected by residual elements.

In this talk, we use nanoindentation, micro-pillar compression, and micro-cantilever bending experiments to identify the residual element that has the most detrimental effect on the microstructure and properties of our lath martensite. Then, proceed to determine the most impacted microstructural feature of our microstructure as well as the predominant damage mechanism in the steel samples.

Keywords: Residuals; Nanoindentation; Interfaces; Micro fracture