Effect Of Surface Nanocrystallization Treatment On Microstructure And Toughness Of Magnesium Alloy

The development prospect of magnesium alloys has been increasingly attracting under the realistic background in pursuing environmental protection and lightweight.However,Mg alloys often be obstructed during application due to its deficiency of ductility and strength at room temperature.In this study,the room-temperature tensile test was carried out on the hot-rolled AZ31 B magnesium alloy at different orientation relative to the rolling plane,and the plastic deformation mechanism of specimens with different angles were studied.The results showed that.The texture of AZ31 B magnesium alloy hot-rolled sheet exists in the form that the(0001)basal plane of most grains is parallel to the rolled plane.The prismatic slip participates in the deformation as the main mode,meanwhile,a small amount of compassion twins was discovered in the process.At 45 °angle between specimen and rolling direction,the basal slip was in a soft orientation,and the plastic deformation of magnesium alloy is determined by basal slip.When the magnesium alloy is stretched in parallel rolling direction at room temperature,the tensile direction is parallel to the crystal c-axis.Currently,the main deformation mechanism of the tensile is tensile twinning.Similarly,the circular flaky samples were cut at different angles from the rolled surface.The tensile properties of surfece-nanocrystallized AZ31 B magnesium alloys with different orientation at room temperature were tested.Three projects have been analyzed in surface-nanocrystallized magnesium alloys with different angles: the deformation difference between different layers,the transfer mode and the mechanism of shear strain while stretching process.The results indicate that.After SMAT,the 0°and 45°samples showed similar gradient structures with grains that is growing increasingly with increasing depth.In the gradient structure,there are two main deformation zones in gradient structure: large deformation fine grain zone and deformed coarse grain zone.When the SMAT 0° sample is stretched by a 600μm sample,the two main deformation zones are independently deformed,relatively.The fine grain zone hinders the high strain of the coarse grain zone because of the internal slip angle relationship,and the deformation is relatively independent.The fine grain zone hinders the high strain performance of the coarse grain zone.During the stretching process of SMAT 45° 600μm samples,the obvious strain transmission and slip continuity between the two layers.The interface between the non-uniform deformed gradient structures allow dislocations to accumulate in the whole sample.This produces significant strain hardening,which enhances the comprehensive properties of the material.Figure 30;Table 3;Reference 92...