Characterization of the Thermophysical Properties of Riser Sleeve Materials and Analysis of Riser Sleeve Performance

Riser sleeves are an effective tool in the steel foundry industry for minimizing riser size and increasing casting yield. Reliable simulation of the performance of riser sleeves requires accurate temperature dependent thermophysical properties. Unfortunately there is little or no such property data available in the open literature. A limited number of sleeve manufacturers provide advice and properties as “black box” databases. The “black box” temperature dependent property data and boundary conditions are proprietary, hidden from the simulation software user. Validated sleeve properties that are openly available to modelers are as necessary as the “open” mold and metal properties they routinely use in designing casting processes. Here a procedure for determining sleeve thermophysical properties and its results are presented. In the procedure, temperature dependent properties of several commonly used sleeve materials are determined through achieving agreement between measured and predicted temperatures throughout the casting process. In order to address the lack of information regarding optimal use of riser sleeves, the performance of different sleeve materials is analyzed using the properties in casting simulations. The modulus extension factor, a quantity which describes sleeve performance, is calculated for several sleeve materials. Analyzing the effect of sleeve performance characteristics on casting yield, it is found that the exothermic reaction provides no discernable advantage to casting yield improvement unless it also increases the modulus extension factor, regardless of casting size for the sleeves tested in this study. From the analysis of the effect of sleeve thickness on casting yield, it is found that most commercially available riser sleeves have thicknesses which are too small to maximize the casting yield, particularly for risers of 8” diameter and larger.