The entrapped slag is one of the main defects on the surface of ultra-low carbon steel hot-rolled coil, the overall macroscopic morphology of the defect is black color or black - white strip, and there is obvious difference with the base sheet, intermittent distribution along the rolling direction, the length varies, often accompanied by warping defects. The incidence of head billet, water change port billet and tail billet entrapped slag is significantly higher than normal billet; large fluctuations in liquid level and superheat over low, will increase the rate of entrapment defects.
According to the law of defect occurrence, the head billet, water change mouth billet and level fluctuation billet and other non-stationary billet flame cleaning, can significantly improve the surface quality of hot rolled coil.
Continuous casting process of immersion water spout side hole is easy to form nodules, mainly due to the high oxidation of ladle slag, thus disturbing the flow field of the mould. It is necessary to increase the depth of immersion in the water outlet and improve the purity of the steel.
Mainly from the intermediate ladle open pouring control such as fast rise pulling speed, intermediate ladle filling argon, open pouring slag to join, reduce the number of bonding alarms such as adjusting the mould protection slag and optimize the vibration of the mould, quality of tail billet and non-stationary pouring during the pulling speed, etc.
The bubble blown into the mould is to prevent the water mouth blockage, but the bubble will be blown into the steel / slag interface rupture, the formation of foam slag and easily involved in the steel. In the case of not increasing the blockage of the water mouth, try to reduce the flow of argon.
In the continuous casting process, the rate of slag inclusion defects can be reduced greatly when the superheat temperature is improved.
The viscosity of the protection slag is small, the liquid slag will be involved in the mould by the steel flow; thus improving the viscosity of the protection slag can reduce the protection slag trapped.
