TY - THES

T1 - Evaluation of the influence of selected tramp elements on the inclusion behavior in the steel matrix

AU - Gruber, Isabell

N1 - embargoed until 26-11-2029

PY - 2024

Y1 - 2024

N2 - In order to achieve the UN sustainability goals and carbon neutrality in the European Union by 2050, it is necessary to increase the share of steel produced via the electric arc furnace route with scrap as secondary raw material. This, however, will inevitably lead to accumulation of certain tramp elements in the steel cycle over time due to the impossibility of removing these elements from the steel melt. The most important ones are copper, nickel, tin, and molybdenum. While the influence of alloying elements in steel is well known, work still needs to be done on how they affect the material and thus the finished product in trace amounts. Furthermore, research about how these elements influence non-metallic inclusions in steel still has to be conducted. Therefore, in this work three medium-carbon steels were alloyed with different amounts of the aforementioned tramp elements and experiments regarding macro- and nano-hardness, deformation behavior, and phase transformation and the resulting microstructure after quenching were performed. The samples were metallographically prepared and investigated under the light microscope and the scanning electron microscope where it was shown that already small quantities of especially copper affected the samples¿ surface quality. It was further demonstrated that macro-hardness was not influenced by tramp elements. However, they affected phase transformation points and the resulting microstructure. Albeit no conclusive statements can be made about the deformation behavior with and without tramp elements, they did influence deformation flow stress of the material on a macroscopic change. No statements can be made about the tramp elements` effect on nano-indentation.

AB - In order to achieve the UN sustainability goals and carbon neutrality in the European Union by 2050, it is necessary to increase the share of steel produced via the electric arc furnace route with scrap as secondary raw material. This, however, will inevitably lead to accumulation of certain tramp elements in the steel cycle over time due to the impossibility of removing these elements from the steel melt. The most important ones are copper, nickel, tin, and molybdenum. While the influence of alloying elements in steel is well known, work still needs to be done on how they affect the material and thus the finished product in trace amounts. Furthermore, research about how these elements influence non-metallic inclusions in steel still has to be conducted. Therefore, in this work three medium-carbon steels were alloyed with different amounts of the aforementioned tramp elements and experiments regarding macro- and nano-hardness, deformation behavior, and phase transformation and the resulting microstructure after quenching were performed. The samples were metallographically prepared and investigated under the light microscope and the scanning electron microscope where it was shown that already small quantities of especially copper affected the samples¿ surface quality. It was further demonstrated that macro-hardness was not influenced by tramp elements. However, they affected phase transformation points and the resulting microstructure. Albeit no conclusive statements can be made about the deformation behavior with and without tramp elements, they did influence deformation flow stress of the material on a macroscopic change. No statements can be made about the tramp elements` effect on nano-indentation.

KW - Spurenelemente

KW - Stahl

KW - Nichtmetallische Einschlüsse

KW - Steel

KW - tramp elements

KW - non-metallic inclusions

U2 - 10.34901/mul.pub.2025.047

DO - 10.34901/mul.pub.2025.047

M3 - Master's Thesis

ER -