Solidification of Electroslag Remelted Low Alloy Steel Ingots.

摘要

The solidification of electroslag remelted AISI 4340 steel ingots was investigated over a range of melt rates from 3.7 to 6.3 lb/min. The liquid metal pool shape was determined by marking the liquidus isotherm with tungsten additions, and these data were used for an empirical model to predict the liquidus geometry as a function of the melt rate. The model is based on the premise that the solidification rate normal to the mold wall is independent of the melt rate. Data on the local solidification time and the axial mushy zone width were obtained from dendrite arm spacing measurements and an empirical relation between the arm spacings and the average cooling rate during solidification. This was combined with information on the liquidus isotherm shape to locate the solidus isotherm. The local solidification time, mushy zone width, and depth of the solidus isotherm are not linear functions of the melt rate. At a high melt rate where the liquid pool depth approaches the ingot radius the rate of increase of these variables with increasing melt rate is significant, and conditions are produced which would be expected to result in solidification-related defects such as macrosegregation. Macrosegregation was investigated by wet chemical analyses at locations from the surface to the center of the ingots. No macrosegregation was observed in the AISI 4340 alloy at either the high or low melt rate. (Author)