Analysis of single crystal casting process taking into account the shape of pigtail

Under the condition of unidirectional solidification of alloy, an engineering model for grain selection has been developed. This is a 2D, deterministic model, depending upon the theory of columnar dendrite growth. This engineering model is applied to single crystal casting process. The ratio between number of well oriented products and total number of trails is defined to be a yield rate. Here, if the direction of [0 0 1] of a selected single crystal is within 10° from the long side of the product, is judged to be well oriented. The parameters for calculation are the angle, width and length of pigtail. The effect of these parameters on the yield rate has been investigated. In the range of this study, the yield rate does not exceed 90%. The yield rate decreases if the angle of pigtail increases or decreases. There are also the most suitable value of the diameter and length of pigtail in order to get high yield rate of single crystal casting.