Deoxidation of mild killed steel - forming spessartite which may be decanted by simultaneously adding cpds. of manganese, silicon and aluminium

摘要

Method for deoxidising mild killed steels (C =0.15%) consists of measuring the amount of O2 dissolved in the molten steel bath before transferring it to the ladle, then forming inclusions consisting in the large majority of spessartite, which are as free as possible of Al2O3 and rhodonite, by adding to the bath a mixt. of materials which are carriers of Mn, Si and Al, esp. the corresponding ferroalloys. The steels-exhibit improved extrudability. The simultaneous addition of the three elements the individual disadvantages of adding them separately. Spessartite is more readily decantable than rhodointe. The dissolved oxygen level in equilibrium is less with spessartite than with rhodonite. Spessartite is liquid at 1195 degrees C with better cralescince than Al2O3, and it does not cause blockage of the nozzles of the continuous casting plant.