Ductility improvement in AZ31 magnesium alloy using constrained compression testing technique

The Mg-base alloys exhibit very limited ductility particularly upon compression at ambient temperature. The objective of present study is to determine the effect of a new process, so-called constraint compression testing, on room temperature ductility behavior linked to microstructural evolution in AZ31 magnesium alloy. The dominant features of the microstructure are mechanical twinning, double twinning, and shear bands combined with formation of new fine grains with a size of about 1-3 μm. The formation of new fine grains during constraint compression is attributed to the room temperature dynamic recrystallization, which is the first-time observation in AZ31 alloy. The combination of twinning and dynamic recrystallization inside the shear bands has been speculated as the main deformation mechanism for the room temperature constraint compression testing. This has as well led to an outstanding grain refinement. More homogeneous grain size distribution is obtained when the strain is increased from 0.20 to 0.55. The obtained results indicate that the elongation to fracture of AZ31 is enhanced from 0.18 to 0.55 in this process.