FACTORS AFFECTING SHRINKAGE CAVITY FORMATION IN GREY IRON CASTINGS

Document Type : Original Article

Authors

1 Department of Materials and Processes, Military Technical College Cairo, Egypt.

2 Helwan Iron Foundries, Cairo, EGYPT.

Abstract

Shrinkage cavity formation in grey iron castings was investigated using, special mould arrangement allowing easy determination of the shrinkage. volume after solidification. The effect of melt chemistry was studied' by variation of carbon equivalent from 3.59% to 4.59% and determination of the corresponding change in shrinkage volume. The effect of silicon content in the melt for the same carbon equivalent CE is also tested to show the effect of silicon content on shrinkage amount. The relation between eutectic graphite content and the shrinkage volume in grey cast iron ingots was evaluated. Low shrinkage values were observed at high eutectic graphite contents. Effect of pouring temperature on the shrinkage volume was evaluated using five different pouring temperatures 1180 00,1200e, 1250 C°, 1285 C° and 1320 C° while keeping all other casting conditions constant. Shrinkage volume of grey cast iron was found to increase by increasing pouring temperature. The effect of mould rigidity on grey iron shrinkage was evaluated using different moulding materials. High shrinkage volumes were observed at low rigidity moulds. The control of phosphorous content in the melt was found to reduce the sensitivity of measured shrinkage volumes to variation of mould rigidity.