Abstract
Cast commercial magnesium alloy AZ31 was processed by high pressure torsion (HPT) at room temperature for 1, 3, 5 and 15 rotations (strain ranged from 1 to 7). Microstructure evolution with strain imposed by HPT was observed by light and electron microscopy.
HPT was shown to be a very effective method of grain refinement. The initial coarse grain structure was refined by a factor of almost 200 already after one HPT turn (ε ALMOST EQUAL TO 4).
Mechanical properties were investigated by detailed 2-D microhardness measurements. HPT straining was found to introduce a radial inhomogeneity in the material which is manifested by a pronounced drop in the center and the maximum near the specimen periphery.
With increasing strain due to HPT this inhomogeneity is continuously smeared out tending to saturate with increasing strain. Integrated 3-D meshes across the total surface of disks revealed the undulating character of microhardness variations.
The strain imposed by HPT was shown to saturate with increasing number of HPT turns.