Background

Ongoing experimental research aims to understand how NMI-modification using alkali element compounds works and how this can lead to improved mechanical properties of cleanness-sensitive steel products. In theory, incorporation of alkali elements such as Lithium, Sodium, or Potassium could lead to increased deformability of otherwise hard and non-deformable oxidic NMIs, such as Al2O3. In previous research, such a modification was achieved using Na2CO3 and K2CO3. Yet to understand are the mechanisms behind those modifications, as additional experiments are necessary to observe if the alkali elements interact with pre-existing oxidic particles, for example Na2O or K2O, or if prior reduction to their metallic counterparts, respectively, is necessary.

Objective

In this work, several experiments should be performed with accompanying analytical methods to gain a deeper understanding of mechanisms during the secondary refinement of cleanness-sensitive steel grades. These experiments include melting and refinement practices of multiple steel grades on a laboratory scale, such as carbonate modification experiments and steel-slag interaction experiments. The obtained samples should be subjected to detailed analysis using state-of-the-art SEM/EDS methods and Inclusion analysis. The results need to be interpreted to bring clarity to the reaction path of different alkali-element-containing compounds during the modification of non-metallic inclusions in the steel. Additional thermodynamic calculations using
FactSage should aid in the development of a comprehensive reaction model describing the mechanisms in the melt during the secondary refinement steps.

Scope