Paper Title
MATERIALS CHARACTERIZATION EVOLUTION OF HARDNESS, MICROSTRUCTURE AND CORROSION BEHAVIOR OF AZ91 MAGNESIUM ALLOY AFTER HIGH STRAIN MULTI-AXIAL FORGING

Abstract
Abstract - Magnesium alloys have been considered due to its high strength to weight ratio. In this study,cubic samples of as-cast AZ91 were cut in the dimension of 1  1  1 cm3, and then a hot severeplastic deformation process was applied on them at 350 C. The samples were continuouslycompressed in the direction of x, y and z. The raw samples and one, two and three-directionalforged samples were evaluated by Vickers hardness, potentiodynamic polarization, scanningelectronmicroscopy(SEM),andelectrochemicalimpedancemethods.Vickershardnessevaluation showed that by applying forging in three continual directions, the hardness of the rawsample increased from 74 HV to 86 HV. However, by increasing the number of forging pass, thecorrosion current density decreased from 2 mA/cm2 to about 6.9 10-4 mA/cm2. SEM evaluationindicated that corrosion zones were reduced by increasing deformation. Polarization resistanceobtainedfromelectrochemicalimpedancemethodincreasedfrom381.99to1914.4.cm2related to the as-cast and three-directional deformed samples, respectively. The event confirmedthat anodic regions reduced on the surface of forged samples. The mentioned results confirmedthe positive effect of grain size reduction, applied compressive strength and blocking of thepresentedmicro-voids on the corrosion behavior ofthealloy. Keywords - Sever plastic deformation; Corrosion; Hardness; Polarization