SOLIDIFICATION AND SEGREGATION OF LARGE KILLED STEEL INGOTS.

The results of the investigation show that the solidification pattern in large flat steel ingots is proportional to the square root of time after teeming in the first stage solidification and proportional to the square of time with the formation impurity precipitates. Skimming of the liquid steel in the mold makes the inverse V segregation disappear in the top surface of the ingot, but it remains in the ingot bottom. Further, the inverse V segregation lines become thin and shift to the inner parts of the ingot. Formation of inverse V segregation is closely related to solidification velocity. The critical solidification velocity becomes small by skimming. By RE metal addition to the liquid steel in the ladle, the inverse V segreg lines in sulfur prints become the white segregation, and occurrence of large inclusions is insignificant.