Behavior of Slag Inclusions during Solidification of a Large Forging Ingot

Abstract

In order to investigate the behavior of slag inclusions during solidification process of large forging ingots, granular mixtures of the synthetic slag and Fe-1%P alloy uniformly containing fine Si0₂ inclusions were held at the solid-liquid coexisting temperature. On the basis of the experimental results, some discussions were made on the behavior of exogeneous slag inclusions during solidification of a 220 t commercial ingot. The results obtained were summarized as follows; (1) Slag inclusions were found to absorb fine SiO₂ inclusions distributed in the surroundings, resulting in the decrease of CaO content during holding at the liquid-solid coexisting temperature.
(2) The change in CaO content in slag inclusions with the distance from the surface to the center of the ingot was well explained by the dilution model obtained by the experiment.
(3) The maximum diameter of inclusions growing by coagulation during solidification of the ingot was estimated to be 60-70 μm.