TItle：What are the requirements for the mold flux melting mode?
Description：Briefly explain what is the melting mode of mold powder and what are its requirements
The mold flux added to the mold during the continuous casting process must fulfill the functions of the above five aspects. The mold flux powder must have a prescribed melting mode, that is, the so-called powder slag layer-sintered layer one liquid is required to be formed on the molten steel surface. The so-called three-layer structure of the slag layer.
The slag powder with low melting point (1100～1200℃) added to the high temperature molten steel (about 1500℃) surface of the mold, relying on the molten steel to provide heat, forms a certain thickness of liquid slag covering layer on the molten steel surface (about 10～ l5mm), the heat transfer of molten steel to the slag layer slows down, the slag on the liquid slag layer is heated, and the slag powder sinters together to form a so-called sintered layer (temperature at 900～600℃). The slag receives less heat transferred from the molten steel and has a low temperature (<500°C), so it remains in powder form and evenly covers the surface of the molten steel, preventing the molten steel from dissipating heat and preventing the oxygen in the air from entering the molten steel.
During the drawing process, due to the up-and-down vibration of the mold and the downward movement of the solidified shell, the liquid slag layer on the molten steel surface is constantly squeezed into between the shell and the copper wall through the interface between the molten steel and the copper wall. A solid slag film is formed on the surface, and a liquid slag film is formed on the surface of the condensed shell. This liquid slag film acts as a lubrication on the mold wall and the surface of the blank shell, just like adding lubricating oil when the motor shaft rotates. At the same time, the slag film fills the air gap between the blank shell and the copper wall, reduces the thermal resistance, and improves the heat transfer of the crystallization.
As the drawing progresses, the liquid slag on the molten steel surface is continuously consumed, and the sintered layer drops to the molten steel surface and melts into a liquid slag layer. The powder slag layer becomes a sintered layer, and then new slag powder is added to the mold. Keep it in a three-layer structure, so that the protective slag powder is consumed continuously.