Growth of Initial Clog Deposits during Continuous Casting of Ti-ULC Steel – Formation and Reduction of the Initial Deposits at Nozzle/Steel Interface

• Published in: ISIJ International Vol. 60; no. 3; pp. 426 - 435
• Main Authors: Lee, Joo-Hyeok, Kang, Youn-Bae
• Format: Journal Article
• Language: English
• Published: The Iron and Steel Institute of Japan 15.03.2020
• Subjects: continuous casting; nozzle clogging; reduction; reoxidation; Ti-ULC steel
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.ISIJINT-2019-384

In order to elucidate a nozzle clogging mechanism during continuous casting of Ti-ULC (Ti containing Ultra Low C) steel, a series of experiments employing a rotating finger method was employed. In the context of the carbothermic generation of CO – oxidation of Ti-ULC steel at the interface between the nozzle and the liquid steel – reduction of FetO in the oxidized product composed of FetO–Al2O3–TiOx (“FAT”) by the liquid steel, the FAT was intentionally coated on usual nozzle refractories (“CZ”). It was found that the refractory components (CaO, ZrO2, SiO2) rapidly dissolved into the FAT. The FetO in the FAT was rapidly reduced by Al and Ti in the Ti-ULC steel. As a result, reduced Fe metallic droplets mixed with CaO–Al2O3–TiOx–ZrO2–SiO2 oxide were found as the clog deposit. This was in good agreement with the previous reports. In case of pure liquid Fe, the FetO was not reduced but remained in the deposit. A likely reaction mechanism for the growth of the initial clog deposit was proposed.