Effects of Equal Channel Angular Pressing (ECAP) Process with an Additional Expansion-Extrusion Stage on Microstructure and Mechanical Properties of Mg–۹Al–۱Zn

In this study, equal channel angular pressing (ECAP) process with an additional expansion-extrusion stage named expansion-extrusion equal channel angular pressing (EECAP) process is utilized for producing bulk ultrafine grained (UFG) Mg–۹Al–۱Zn magnesium alloy. In this process, cyclic expansion-extrusion (CEE) and equal channel angular pressing (ECAP) processes are combined. AZ۹۱ magnesium alloy was used for this experiment. An FEM simulation was performed to calculate the compressive hydrostatical stress. Furthermore, microstructural and mechanical properties were investigated. The experimental findings revealed that the ductility of the sample remains almost constant (۰.۰۳% drop) while ultimate tensile strength increased about ۳۰%. The average value of microhardness improved from ۴۸ Hv to ۶۵ Hv (۳۵%) and grain size refined from ۱۴۴ µm to ۳.۴ µm. Despite the expansion part of the die, there is no need for back pressure. Another advantage of this new method is maintaining ductility while strengthening.

Keywords:

EECAP , Ultrafine grained metals , AZ۹۱ alloy , Severe Plastic Deformation