Study on initial solidification characteristics of high-Mn steel for ultra-low temperature applications

The formation of cracks and the breakout of high-Mn steel for ultra-low temperature applications during continuous casting processes negatively affect slab quality. This issue is closely related to the initial solidification behavior of molten steel in the mold. This study investigated the effects of molten steel temperature and the cooling intensity of copper plate on the free deformation of solidified shell using the levitation melting technique. It aims to elucidate the initial solidification characteristics of high-Mn steel for ultra-low temperature applications. The results indicate that the solidified shell exhibits a thin, flaky shape with a slight degree of deformation at lower molten steel temperature and smaller cooling intensity. Conversely, at higher molten steel temperature and greater cooling intensity, the solidified shell exhibits a hemispherical morphology with considerable deformation. Additionally, the heat flux density of the copper plate diminishes as the molten steel temperature increases, while it rises with higher cooling intensity within a specific range. The initial solidification structure of high-Mn steel for ultra-low temperature applications is austenitic, characterized by a high thermal expansion coefficient and low thermal conductivity, resulting in relatively large shrinkage stress and thermal stress on the solidified shell. Furthermore, the wettability of molten steel is generally favorable, and it decreases as the molten steel temperature and cooling intensity increases.