Variability of Niyama Values Study

The Materials Technology Institute showed interest in this project with the University of Iowa - Yield program. In particular members of MTI have focused on the Gage R&R study of radiographic film interpretation. The MTI members will often require that castings be radiographed to ensure quality levels are delivered. However, they have continued to look at the issue of casting quality and established a Task Group to examine how they can better specify casting quality. The UI work on leakers has aroused great interest at MTI to the extent that they wish to see how simulation may be included in their own purchasing specifications and possibly incorporated in ASTM and ASME standards and codes. There are already precedents for the requirement of solidification simulation by purchasers.

Clearly different software packages calculate Niyama values at different points during solidification and use different units. There are other variables which must also be considered in the modeling of solidification that are foundry dependent. In order for the use of solidification simulation to be used by purchasers, there is a need to determine the variability that may be expected in the results so that unreasonable requirements that do not benefit the purchaser are avoided.

The attached documents describe the rationale and requirements of the study. The intent is to determine the variability in the Niyama values, it is not to see how good a foundry is at risering a casting. The "stl" files are available below. Although four alloys are shown, it is not necessary for each foundry to simulate all four of the alloys.