Influence of strain rate and temperature on the flow behaviour of magnesium alloy AZ80

The flow and fracture behaviour of the high strength wrought magnesium alloy AZ80 is investigated in quasi-static and dynamic compression tests at strain rates in the range 0.001 s-1 ≤ φ≤ 5000 s-1 and temperatures between room temperature and 300 C. Compression tests at strain rates φ≤ 100 s-1 were carried out using a computer controlled servo-hydraulic testing machine. High strain rate experiments at φ≥ 1000 s-1 were performed on a modified Split Hopkinson Pressure Bar. A constitutive material law, whose parameters are determined from the experimental data, can be applied to describe flow curves in case of high strain rate loading. In addition to the increased strain rate sensitivity, the adiabatic character of the deformation process has to be taken into account for a formulation of the material behaviour under impact compression. Making use of experimentally determined flow curves of AZ80, the influence of strain rate and temperature on the deformation at fracture can be obtained. Additionally, metallographic investigations give explanation about character, origin formation and evolution of damage in the deformed material. (orig.)