The influence of the near-meniscus zone in continuous casting mold on the surface quality of the continuous casting ingots

Abstract

The physical, chemical and mechanical phenomena which take place in the near-meniscus zone of continuous casting mold are the significant factors influencing the quality of CC ingot and especially the quality of its surface. Such phenomena consist of the following processes: lubrication of the ingot surface by the liquid slag-forming phase of mold powder, creation of meniscus, formation of the specific kind of galvanic cell and connected with this cell ions migration of liquid mold powder. Application of the mold powders is the commonly used lubrication method of the surface of CC ingots in mold (in near-meniscus zone). According to the ionic structure theory of the liquid metallurgical slags the following thesis can be formulated: the liquid slag-forming phase of mold powder is the ionic liquid. The ionic liquid occurs between two metals: the copper wall of mold and the steel surface of ingot can create a specific kind of galvanic cell in the upper part of mold (the near-meniscus zone of mold). The paper presents results of industrial research of low-carbon steel continuous casting. The electromotive force of galvanic cell situated in the upper (near-meniscus) part of CC mold was measured. Moreover, the influence of applied powders with different alkalinity on the character of oscillatory marks forming on the ingot surface was considered. The galvanic cell, which is created in the upper part of mold in the near-meniscus zone, can cause the essential change of the chemical composition of electrolyte (liquid phase of mold powder) in the near-electrodes zones. So in the process the condition of lubrication and character of obtained oscillatory mark can also be changed.