Compression Behavior of Near-UFG AZ31 Mg-Alloy at High Strain Rates
The superior specific strength of magnesium alloys makes them very attractive for several applications, especially in transportation, aviation, and space industries. Usually the properties of most metals, including magnesium alloys, can be enhanced by reducing the average grain size, which leads to increasing strength without decreasing the ductility of the material too much. One of the methods used today to decrease the grain size is the severe plastic deformation (spd), where the grain size is decreased by applying a very high shear strain under high hydrostatic pressure, leading to the accumulation of dislocations and eventually forming new smaller grains. Usually the amount of material that can be processed at one time is very limited, making most of the severe plastic deformation techniques less suitable for industrial production. One of the interesting techniques that allows larger batch sizes to be processed at one time is called reciprocating extrusion. In this work, the compression properties of the reciprocating extrusion processed standard magnesium alloy AZ31 were studied in a wide range of strain rates. The results show that the strength of AZ31 is significantly higher after reciprocating extrusion as compared to squeeze cast AZ31, and at the same level as for the hot rolled and ECAP processed AZ31. The compression tests were also monitored using digital cameras, and the surface strain distributions on the specimen were calculated using digital image correlation. The strains on the surfaces of the specimens were fairly homogeneous and no significant barreling was observed. The failure of the specimens occurred at a 45 degree angle in all tests, preceded by a rapid formation of a shear band.
KeywordsMagnesium Alloy Shear Band High Strain Rate Digital Image Correlation Severe Plastic Deformation
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