Continuous casting now produces more than 90 % of the world’s steel an‎d, despite its high capital cost, is the most cost- an‎d energy-efficient means of mass-producing semi-finished metal products. Thin slab casting technology, which reduces slab thickness to about 30–60 mm, shortens the production line, increases casting speed an‎d enhances solidification, thereby improving microstructure an‎d reducing energy consumption. Nevertheless, the reduced thickness makes the process highly sensitive to thermal–mechanical instabilities; inappropriate secondary cooling may lead to surface cracking due to excessive thermal stresses. This thesis develops a two-dimensional thermo-mechanical model for a medium-carbon steel thin slab in continuous casting. In the thermal model, the heat-convection equation with latent heat release is solved using COMSOL Multiphysics 6.2 to predict temperature distribution an‎d solid shell growth. Boundary heat-flux functions for the mold an‎d secondary cooling zones are calibrated using empirical correlations an‎d plant data, an‎d surface temperatures are validated against pyrometer measurements. The resulting shell thickness, metallurgical length an‎d temperature profiles along the center of the wide face are obtained. The mechanical model calculates Thermal stresses an‎d thermal strains along the casting direction, assuming temperature-dependent behavior, an‎d compares the computed stress with the 0.2 % proof strength from JMAT-Pro to assess the risk of yielding. Results indicate that the highest stresses an‎d strains occur in the early segments of secondary cooling at the wide-face center; the stress-to-strength ratio reaches about 0.7 but remains below unity, indicating a limited safety margin. Surface temperatures oscillate between about 850 °C an‎d 1160 °C, an‎d cyclic spray cooling causes corresponding stress an‎d strain fluctuations. Parametric studies show that reducing spray intensity in initial segments an‎d homogenizing the water-spray distribution lower thermal gradients an‎d peak stresses, improving surface quality. The study demonstrates that a two-dimensional model can reliably predict temperature, solidification an‎d thermal stresses in the center of a thin-slab wide face, an‎d that the 𝜂 is a useful criterion for locating critical zones. The results provide a foundation for optimizing secondary-cooling strategies an‎d selec‎ting casting speeds in industrial lines such as the Saba Steel Company an‎d similar facilities.

محسن دوازده امامي

مسعود پنجه پور

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