Modeling of metal delivery systems used in electromagnetic and direct-chill semicontinuous casting of aluminum

The flow of liquid metal in the upper region of an EM (electromagnetic) or DC (direct chill) caster significantly contributes to the solidification behavior and subsequently the final ingot properties (e.g., average grain size and macrosegregation). The characterization of such a flow is a complicated task due to the high operating temperatures and the inherent opacity of the metal. However, as the demand for improved quality and reduced operational costs continues, understanding the mechanics of the flow becomes increasingly important. Hazardous, and often catastrophic, casting defects, such as hot cracks and tears, have been linked to non-uniformities in the solidification front that occur due to improper flow in the liquid pool.; A novel technique to measure the flow, using particle imaging velocimetry (PIV), has been incorporated into a laboratory scale physical model of an aluminum caster. The instantaneous vector plots reveal valuable information regarding the turbulent nature and the intrinsic flow oscillations. However, time-averaged vector plots (TAV), obtained by ensemble averaging instantaneous plots, detail information regarding the average features of the flow. The results show that the method of metal delivery into the ingot significantly effected the flow patterns observed. Computational studies of the model geometry reproduce the same flow profiles adding to the validity of the PIV method. Based on the information obtained through physical modeling, an experimental campaign, on production size ingots, was conducted to determine the influence of the liquid pool velocities on the sump profile. Furthermore, a 3D coupled fluid flow-solidification finite element model was developed as a tool to predict the fluid flow/solid front interaction in an attempt to anticipate non-uniformities in the solid.; The study has shown that the method of metal delivery into the mold, the upper region where solidification initiates, is critical in determining the flow of liquid metal and subsequently the sump profile in the ingot. By understanding the connection between delivery system and flow, informed decisions could be made regarding operational procedures.