The purity of the cast billet is mainly determined by the treatment process before the molten steel enters the mould. How can keep the billet with less inclusions? Currently there are a few methods ito use, such as the appropriate process of refining process, tundish metallurgy, protective pouring operations. The quantity, form and distribution of non-metallic inclusions will influence the purity of the cast billet. It is rather important to take some measures to reduce inclusions of the steel to the required level.
Preventing a large amount of steel slag down to the ladle, converter may use slag ball, electric furnace with eccentric bottom tapping is preferred.
Select the proper refining methods ensure uniform temperature, fine-tune the composition(according to steel grade), lower oxygen content, removal of gas inclusions.
The total oxygen content of the liquid after ladle treatment will be significantly reduced, such as ladle → intermediate ladle pouring is not protected or poor protection, the total oxygen of the liquid in the tundish turns high, there maybe lose the effect of refining the liquid.
To use tundish which has large capacity and reasonable structure(for example V retaining wall, turbulence suppressor, vortex suppressor), that can not prevent suction slag, and also make the liquid mixed evenly.
The nozzle material, nozzle shape and insertion depth should be conducive to floating and separation of inclusions.
