Modelling of critical solid fraction factor depending on mold temperature in aluminium alloy castings

Depending on the rapid developments in computer technology, modeling of casting processes provides a significant prediction for micro and macro porosity of casting. With these technological developments, gating and feeder design of the casting can be made, and micro and macro porosity regions in the casting can be estimated easily. However, casting defects with computer-aided casting design are correctly estimated providing that casting parameters are only properly defined. One of the most important of these parameters is the identification of resistance which is generated solid dendrites against fluidity of the feed liquid at solid-liquid zone. Feeding stops at the interdendritic feeding zone when liquid flow channels in the solid-liquid region are blocked. This event is known as dendrite blockade which is defined as critical fraction of solid (CFS). In computer-aided modeling for metal casting, the value of CFS must be defined correctly to simulate the production of casting.The main purpose of this study is to determine the value of CFS depends on the grain refining, and different mold temperatures. The results of computer simulation are compared with results obtained from the actual castings. It is concluded that following:1. In the non grain refined casting, 100°C, 155°C, and 210°C mold temperatures produced 2,30 cm3, 1,46 cm3, and 1,16 cm3 macro shrinkage cavities respectively. 30%, 40%, and 55% CFS values respectively for those cavities were determined.2. In the grain refined casting, 100°C, 155°C, and 210°C mold temperatures produced 1,70 cm3, 1,25 cm3, and 0,94 cm3 macro shrinkage cavities respectively. 45%, 52%, and 65% CFS values respectively for those cavities were determined.