Influence of a wiper on residual stresses in AA7050 rolling plate ingots

As-cast stresses in the foot of the ingot corresponding to the transient start-up phase of the direct chill casting have been determined in aluminum alloy AA7050 rectangular ingots. This high strength alloy is usually cast with a wiper that is placed below the mold and ejects the falling water from its surface thus reducing the cooling intensity. The ingot being hotter, internal stresses are relaxed. The efficiency of a wiper has been evaluated using both neutron diffraction measurements on ingots cast with and without a wiper and a 3D numerical model simulating the stress generation during casting. The stress level is reduced by 33% when a wiper is used during casting and the stored elastic energy by 50%.