Study of the Clogging of the Submersible Nozzle in the Continuous Casting of Stainless Steel RE-253MA

To prevent clogging of the tundish nozzle during the continuous casting of stainless steel 253MA – which contains an addition of rare-earth metals (RE, REM) and is made in an EAF–AOD–LF system – the phases of the crust formed on the nozzle are studied by x-ray diffraction. The casting properties of the steel are examined in relation to such parameters as the amount of REM used, changes in oxygen content, the length of time the steel is stirred with argon in the ladle-furnace, and the geometric parameters of the nozzle. The results show that the compounds RE₂O₂S and RE₂O₃ and the steel participate in the formation of the crust. Also, specific measures are proposed to optimize the shape of the nozzle, improve the cleanliness of the steel, prevent secondary oxidation of the steel in the caster strand, and reduce the number of REM-inclusions by removing SiO₂ inclusions and gently stirring the steel with argon before the addition of the REM and a Ba alloy. Alternative methods are proposed for optimizing the parameters of the process of alloying the stainless steel with rare-earth metals.