EVALUATION OF LASER-BASED OXIDE REMOVAL AS AN ALTERNATIVE TO ACID PICKLING IN CONTINUOUS FLAT STEEL PROCESSING LINES: ENERGY CONSUMPTION AND GREEN TRANSITION PERSPECTIVE

Date

2026-4-20

Author

Çelikses, Eren

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The steel industry's transition towards decarbonization necessitates sustainable alternatives to conventional, energy-intensive, and environmentally hazardous hydrochloric acid pickling processes. Laser-based descaling has emerged as a promising chemical-free surface preparation technology; however, its industrialscale integration for hot-rolled flat steels is hindered by the complex, multi-layered nature of oxide layer (wüstite, magnetite, and hematite) and a lack of comprehensive economic feasibility studies. This thesis systematically investigates the feasibility and operational efficiency of employing a 1070 nm fiber laser for descaling hotrolled flat steels. The study employs a multi-stage methodology, beginning with the microstructural and morphological characterization of the oxide layer, including thickness variation analysis and phase distribution mapping via Electron Backscatter Diffraction (EBSD). Subsequently, UV-Vis-NIR spectroscopy is utilized to determine the phase-dependent optical absorption characteristics, providing a scientific basis for optimal laser interaction. A rigorous parametric experimental study is then conducted using both Continuous-Wave (CW) and Pulsed-Wave (PW) laser modes to evaluate ablation efficiency, monitor phase transformations, and define the optimal operational window. Finally, the research correlates the achieved laser cleaning speeds with energy consumption metrics to perform a comparative industrial feasibility analysis against conventional Continuous Pickling Lines (CPL). Additionally, comparative surface integrity analyses revealed that the selected lasercleaning parameters resulted in higher surface roughness, a laser-affected nearsurface region of approximately 10–22 µm, and localized hardness increase compared with conventional pickling, highlighting the need for further parameter optimization, particularly for products subjected to subsequent cold rolling. Ultimately, this study aims to provide a robust scientific and economic foundation for the implementation of laser descaling technology in modern, high-speed steel production lines, contributing significantly to the industry's green transition initiatives.

Subject Keywords

Flat Steel Production, Hot-Rolled Steel Oxide Scale Characterization, Laser-based Oxide Removal, Carbon Footprint Assessment, Green Transition

URI

https://hdl.handle.net/11511/119423

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Graduate School of Natural and Applied Sciences, Thesis