Influence of Mg additions on the microstructure and composition of oxide inclusions in iron-based alloys

Non-metallic inclusions, including oxide, sulphides and nitrides, are commonly found in steels as a direct result of steelmaking and thermal treatment processes. Despite representing a small percentage of the steel’s composition, inclusions have a significant influence, generally detrimental, on the mechanical properties of steel. The structure and composition of non-metallic inclusions in steels are a direct consequence of the deoxidation practice, which involves the addition of elements with high oxygen affinity like Al, Si, Mn or Ca. The resulting variety of oxide inclusions remain inevitably in the iron-based matrix in spite of the extensive use of several steel cleaning strategies. In this context, the modification of oxide inclusion’s composition and microstructure through small Mg additions may have a substantial impact on their local mechanical properties and ultimately on their role during deformation of the whole iron-based alloy.

In this semester project, the student will investigate the influence of Mg addition to specific oxide inclusion containing samples within the Si-Al-Mn oxide pseudo-ternary phase diagram. To such end, the student will produce lab-scale samples by following a multi-step melting procedure, already optimized during previous works at the LMM for certain oxide inclusion stoichiometries, to then explore different routes for inclusion modification through controlled Mg additions. Then, specimens will be prepared by standard metallographic techniques for microstructural and compositional evaluation, including optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

Responsible supervisors: Sándor Lipcsei and David Hernández Escobar
Contact: [email protected] and [email protected]