Development of new feeding-distance rules using casting simulation: Part I. Methodology

A methodology is developed to relate measured shrinkage porosity levels in steel castings to predictions from casting simulations, in order to determine feeding distances. Low-alloy steel casting trials were conducted to acquire a statistically meaningful set of experimental data for top-risered cast steel sections having various ASTM shrinkage X-ray levels. Simulations of the casting trials were then performed, using casting data recorded at the foundries. during the trials. The actual casting soundness resulting from these trials, measured in terms of the ASTM shrinkage X-ray level, is quantitatively compared to the soundness predicted by simulations, measured in terms of a local thermal parameter known as the Niyama criterion. A relationship is shown to exist between the X-ray level and both the minimum Niyama criterion value as well as the area (in the plane of the X-ray) with Niyama values below a threshold value. Once the correlations developed in Part I of this article were established, an extensive set of additional casting simulations was performed to determine the feeding distances for castings with a wide variety of casting parameters. These data were then used to develop a new set of feeding-distance rules, which are given in Part II of this article.