Doctoral Dissertations

Keywords and Phrases

Continuous casting; Fiber Bragg gratings (FBG); High-temperature inline sensors; Optical frequency-domain reflectometry (OFDR); Raman spectroscopy; Steelmaking

Abstract

Fiber-optic sensors are an emerging technology that can enhance process monitoring and control in steelmaking. They are especially valuable in the continuous caster’s harsh environment. This dissertation presents the industrial application and demonstration of three sensor types: single-mode silica fiber with Rayleigh-based Optical Frequency Domain Reflectometry (OFDR), sapphire fiber (single-crystal alumina) with Fiber Bragg Gratings (sFBG), and an in-line Raman spectroscopy probe. Each sensor served a distinct role in the continuous caster. Rayleigh OFDR sensors were embedded in tundishes for distributed thermal mapping at 7-mm spatial resolution across ≈4 m. Measurements were taken during preheating, casting, and ladle exchanges, and they revealed refractory dry-out and nonuniform heating, consistent with steam buildup and possible hydrogen ingress. A sapphire FBG probe, with three FBGs over 38 cm, provided thermal profiling of the tundish bath and the approximate slag–metal interface during long casting sequences. This detected level changes and thermal stratification (readings ≈7 in. deeper were ~10–15 °F hotter than the operator thermocouple depth). A sapphire FBG was embedded in the sidewall of a submerged entry nozzle (SEN) and captured axial temperature gradients during preheating. A Raman fiber probe collected spectra for high-temperature flux analysis near 1400 °C in the mold. These industrial trials demonstrated sensor packaging, survivability, and process-relevant signal measurements in continuous-caster production environments. Integrating these sensors in the continuous caster revealed new signals for future control and monitoring and advanced real-time process awareness in steel manufacturing.

Advisor(s)

O'Malley, Ronald J.

Committee Member(s)

Smith, Jeffrey D.
Huang, Jie
Bartlett, Laura
Buchely, Mario F.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2025

Journal article titles appearing in thesis/dissertation

Paper I, found on pages 63–89, has been published in Iron & Steel Technology, in July 2024.

Paper II, found on pages 90–115, has been published in the proceedings of AISTech Iron & Steel Technology conference proceedings in Nashville, TN, in May 2025.

Paper III, found on pages 116–147, has been published in the proceedings of MOLTEN 2024: 12th International Conference on Molten Slags, Fluxes and Salts, Brisbane, Australia.

Pagination

xv, 165 pages

Note about bibliography

Includes_bibliographical_references_(pages 159-162)

Rights

© 2025 Hanok Wondimagegnehu Tekle , All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12579

Download

Share

 
COinS