GOALI/Collaborative Research: Understanding Formation and Removal Mechanisms of Micron-sized Non-metallic Inclusions in Steel Refining by Computational and Experimental Studies

Steel is one of the most versatile structural materials and has played a vital role in history and societal advancements. With the increasingly harsh environments demanded of steel, steelmaking requires strict engineering of chemistry, microstructure, and surface and interior quality characteristics of the ladle - the vessel used to transport and pour out molten steel.

In steelmaking, steel cleanliness, defined as the amount and size of non-metallic inclusions, is a critical issue and directly influences both subsequent processing steps and the quality of steel products. Micron-sized non-metallic inclusions are typically removed using argon and/or electromagnetic stirring. These processes, though very difficult, are crucial to minimize such inclusions for lightweight high-performance components.

The lack of fundamental knowledge of complex mechanisms and the ability to quantify the formation and transport of inclusions has hindered progress in the inclusions control in ladle refining. This Grant Opportunities for Academic Liaison with Industry project, collaboration between two institutions and two steel companies, pursues fundamental research on the formation and removal of micron-sized non-metallic inclusions during liquid steel refining in a ladle.

The strong partnership in this project uniquely facilitates the know-how transfer to steel manufacturers with improved product quality and productivity, and therefore, increases the competitiveness of U.S. steel and relevant industries. The award will also provide students with opportunities of academic and industrial research and the project results will be showcased in outreach events to inspire K-16 students to pursue STEM education and careers.

To tackle the challenge associated with inclusions in a ladle refining process, this project aims at obtaining basic knowledge that will address such questions as: what are the mechanisms that generate micron-sized inclusion particles during argon and/or electromagnetic stirring; can flow shear instability at the slag/steel interface generate micron-sized inclusions and are slag-based inclusions the primary source to the total concentration of non-metallic inclusions in molten steel? The team will integrate computational fluid dynamics (CFD) modeling with laboratory water modeling and microfluidic experiments as well as on-site measurements in steel plants for fundamental studies.

The outcomes of the project are expected to provide the following technical insights: (1) the relationships between flow instability at the steel-slag interface, slag-based inclusions, and the total amount of non-metallic inclusions, (2) the quantitative effects of stirring rate on the slag inclusion generation and entrainment, as well as inclusion flotation, (3) experimental technique and methodology for validating the CFD model, and (4) a high-fidelity comprehensive three-dimensional multiphase multi-scale, multi-physics, and multi-species CFD model for steel ladle refining, which can be employed to provide best practice guidance for steel cleanliness control and high-quality mass production.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.