Dynamic Deformation Behavior and Microstructure Evolution of 5000 Series Aluminum Alloys

The aim of the present study is to investigate strain rate dependency of Al-Mg alloys within a wide range of strain rates. Tensile tests of a wide range of strain rate are carried out using Instron universal, servo-hydraulic impact and split-Hopkinson bar testing machines. Also, strain rate sensitivity is evaluated by test of changing the strain rate. The SEM technique is used to analyze the fracture surface characteristics of deformed specimens. The negative strain rate dependency shows at strain rate region between 4.3 × 10^-4 and 1.0 × 10²s^-1 for Al-Mg alloys. However, the extent of rate sensitivity over 1.0 × 10²s ^-1, ultimate tensile strength increases with increasing strain rate. Although the shear dimple type fracture surface is mainly observed under static loading condition, normal type dimple fracture surface is found under high strain rate. The fracture behavior under the variation of strain rates is also discussed based on the results of the microstructure observation.