Experimental investigation of thermomechanical effects during direct chill and electromagnetic casting of aluminium alloys
The deformation and the temperature field within direct chill (DC) and electromagnetic (EM) cast aluminum ingots have been measured in-situ using a simple experimental set-up. The deformation of the cross section of the cold ingots has also been characterized as a function of the casting speed, alloy composition and inoculation condition. The pull-in of the lateral rolling faces has been found to occur in two sequences for DC cast ingots whereas that associated with EMC was continuous. The pull-in was maximum at the center of these faces (about 7-9%) and strongly depended upon the casting speed. Near the short sides of the ingots, the deformation was only about 2% and was nearly independent of the casting parameters and alloy composition. Based upon these measurements, it was concluded that the pull-in of the rolling faces was mainly due to the bending of the ingots induced by the thermal stresses. This conclusion was further supported by a simple two-dimensional thermoelastic model.