Progress in the Development of Improved Feeding Rules for the Risering of Steel

Based on results from computational studies and plate casting trials, deficiencies in the steel casting feeding rules as currently published by the Steel Founders’ Society of America (SFSA) were determined. A methodology for the development of improved steel casting feeding rules was established based on the Niyama criterion determined from simulation. Newly developed feeding rules using this methodology are presented for numerous configurations. Unlike the current SFSA rules, these rules do not depend on the type of plate geometry cast (bar, semi-plate or plate), and are applicable to wider ranges of casting section width to thickness ratios than are the old rules. The feeding distances given by the new rules are longer than the old rules, in most cases about two times the feeding distances given by the old rules. It is demonstrated that use of the new rules leads to typical yield improvements of about 5%, and can increase the yield by up to 14% over castings risered using the current SFSA rules. The existing SFSA guidelines for riser dimensioning are shown through simulations to be valid and entirely adequate. Results from casting trials performed by foundries participating in this project show that the new rules are more accurate than the current rules. In addition, the new rules offer a straightforward methodology of tailoring the feeding of the casting to allow for more or less porosity. This concept of built-in “shrinkage by design’’ can lead to still higher yields on castings with less restrictive non-destructive testing requirements.