BEHAVIORS OF MACRO-SEGREGATES IN THE SAND CAST INGOTS SOLIDIFIED WITH THEIR AXIS INCLINED

Studies on the Solidification and Segregation of Larger Steel Ingots-III

Abstract

In the 2nd Report, the effect of gravity on the vertical segregation proceeding in the melt of solidifying core of ingots has been indicated from a new standpoint.
To know this phenomenon more explicitly, four ingots weighing 4.9 tons with round section were cast in sand moulds (Fig. 1), and the moulds were held either vertically or inclinedly, otherwise alternately inclined and re-erected, during solidification.
Investigations on these ingots (Fig. 3-8) revealed the following facts:
1) The V-segregates are formed even in the zone of negative segregation, confirming some of the previous views.
2) The "germs" of V-segregates are already formed in the solidifying melt, which are fixed as V-segregates when the solid-liquid interface passes them. At some stage of solidifi-cation, they can move independently of the growing crystals.
3) When a solidifying ingot is inclined (22-25°C in this experiment), the germs of V-segre-gates in the melt move towards the direction of the new perpendicular. While, when the ingot is solidified inclinedly from right after the pour, the V-segregates disappear within the half of lower level of gravity.
These show that the effect of gravity on the formation of V-segregates is very conspicuous and delicate.
4) The effect of inclination is also notable for inverse V-segregates.
5) Convection in the solidifying melt seems to be negligible.