Towards spherical alumina inclusions in iron alloys

Non-metallic inclusions, such as oxide and sulphides, are commonly found in steels as a result of current steelmaking practices and subsequent thermal treatment. Despite representing a small percentage of the steel’s composition, these inclusions have a significant influence on several properties of steel, including its formability, toughness, machinability, and corrosion resistance. Generally, they have a detrimental effect and are hence considered undesirable, although sometimes, depending on their size, composition, and distribution, some inclusions can also have a beneficial impact on steel properties.
The structure and composition of non-metallic inclusions in steels are mainly determined by the deoxidation practice, involving the addition of elements like Al, Si, or Mn, and can also be influenced by the alloy’s chemical composition and/or any subsequent thermal treatments. Previous works in the laboratory have successfully produced spherical silica inclusions, from which their strength and ductility have been determined by micromechanical testing; however, no reproducible method to produce spherical alumina inclusions has been obtained so far in our work; this would be the overarching goal of the proposed semester project.
To this end, the semester student will investigate the potential of spherical oxygen-rich inclusions (i.e. manganese silicate), which are liquid at steelmaking temperatures, to transform into alumina inclusions upon reacting with aluminum additions while maintaining their original shape. The student will be involved in the production of iron alloys containing inclusions using laboratory induction melting techniques. Afterwards, the student will analyze the samples using standard metallographic techniques, including optical microscopy and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).

Responsible supervisor: David Hernández
Contact: [email protected]