Tensile behaviour of semi-solid industrial aluminium alloys AA3104 and AA5182

Tensile tests with as-cast industrial aluminium alloys AA3104 and AA5182 were carried out in the semi-solid state to determine the constitutive behaviour at the final stage of solidification during direct chill casting. The behaviour is dominated by the solid network but the geometry of the liquid determines how much of the solid network contributes to the strength. Using a geometrical model, the fraction of liquid which covers the grain boundaries is calculated. This value rises steeply with increasing liquid fraction, which should be taken into account in any modelling of tensile behaviour of semi-solid material. A simple modification of a standard creep law, which takes into account the geometry of the liquid film, provides a continuous description of the constitutive behaviour of these alloys from the creep regime into the semi-solid state.