Fracture behavior and mechanical properties of high strength aluminum alloys in the as-cast condition

Finding a criterion for cold cracking during direct-chill (DC) casting of high-strength aluminum alloys seems to be quite necessary in aluminum industry. However, lack of experimental information on the fracture mode and temperature dependence of mechanical properties of such alloys in as-cast conditions (without any homogenization or stress relieving) makes computer-simulation results unreliable. Mechanical tests on AA7050 and DC-cast A7475 revealed that these alloys lose their ductility sharply as the temperature falls and fail in inter/transdendritic mode. Formation of pores and micro-cracks especially at the matrix-intermetallics interfaces apparently results in brittleness of the material in the as-cast condition. (C) 2008 Elsevier B.V. All rights reserved.