Peiman Garmroodi - MSc student, Mechanical Engineering Department, Sharif University of Technology, Tehran
Ahmad Assempour - Professor, Mechanical Engineering Department, Sharif University of Technology, Tehran

In recent years, severe plastic deformation processes have been used to modify metals' microstructure. One of the most effective methods is known as Equal Channel Angular Pressing (ECAP). In this research, the ECAP process has been used to improve the mechanical properties of magnesium alloy. AZ۹۱ magnesium alloy was processed by ECAP at ۲۵۰, ۳۰۰, and ۳۵۰ °C, and the average grain size was measured using an optical microscope. The results show that the smallest average grain size was obtained at ۳۵۰ ° C. The processed material's microstructure showed a bi-modal distribution in the aspect of the grain size. The process was performed up to four passes. The effect of multiple passes on the mechanical properties and microstructure of the experimental sample was investigated using a Vickers microhardness test and optical microscope. The results obtained from optical microscope images showed a reduction in grain size from ۱۵۰ to ۳ microns. The microstructure of the material became more homogeneous as the pass number increases. The microhardness test results showed a ۳۱.۴% improvement in the hardness of magnesium after four passes. Magnesium hardness increased from ۶۶ to ۷۷ HV after the first pass and ۸۷ HV after the fourth pass of ECAP.

ECAP, magnesium, AZ۹۱, grain refinement, mechanical property