A Metallurgical Study of Oxide-Base Slag Used for Electroslag Remelting

Abstract

The applicability of oxide-base slag were examined, because fluoride-base slag, usually used for electroslag remelting, sometimes accompanies fluorine emission during remelting. CaO-Al₂O₃-base slag were chosen and remelting were carried out by furnaces with 80 mm in diameter and with 360 mm. Operational characteristics and qualities of ingot were assessed in comparison with fluoride-base slag. Results obtained are as follows:
(1) There is no trouble in operation with oxide-base slag with no fuming and good electric stability.
(2) Tendency to form heterogeneous slag skin is improved by a small addition of CaF₂.
(3) Behaviors of elements are little affected with oxide-base slag because of the low activity of iron oxide in slag. Furthermore, excellent deoxidation and desulphurization are attained.
(4) Because oxide-base slag has a small partition ratio of hydrogen, (H) J [H], remelting must be carried out more carefully to the moisture of slag. During remelting, however, the effect of the moisture in atmosphere is a little because of small transfer coefficient of hyrogen through gas-slag interface.
(5) Power consumption decreases about 20-40% with oxide-base slag. Accordingly, it may be possible that CaO-Al₂O₃-base slag takes the place of fluoride-base slag.