Analysis of solidification in Bridgman furnace as simulation of DC casting of aluminium alloy slabs

Abstract

The vertical Bridgman directional solidification equipment has been used in several investigations to simulate direct chill casting of wrought aluminium alloys. As a basis for such investigations and alloy developments, it is important to have an understanding of the performance of the furnace used during simulation of the casting conditions. In this investigation the thermal conditions in the furnace have been analysed in detail, both by measurements and by mathematical modelling. The growth characteristics of the furnace, such as gradient, growth rates and cooling rates have been compared to conditions in large ingots. The direct chill casting conditions, which the simulations have been compared to, are casting of slabs of 330 and 600 mm thickness of an aluminium AA3003 type alloy. The results show that the experiments are able to simulate the cooling conditions in the ingots except from the surface zone. Comparisons of the microstructures have been made and a good agreement has been obtained for structure parameters such as grain size and DAS.