Mechanism Analysis Of Plastic Deformation Of Magnesium Alloy Bars

Magnesium and its alloys are the lightest metal materials,as the product lightweight has currently attracted attentions,magnesium and magnesium alloys have great potential application prospects in fields of aeronautics and astronautics,motor industry,3C products and medical instrument production.In this paper,the commercial extruded AZ31 magnesium alloy rods were chosen as the research object.By processing it becoming standard samples.The uniaxial tensile and compressive deformations and torsion of extruded mg alloys rods were carried out under various conditions.The mechanical properties of the specimens during deformation and the changes of microstructure before and after deformation were studied.The different of grains orientation of simples and the types of activated twin variants during deformation were studied by the electron backscatter diffraction technique.The main conclusions are as follows:(1)The uniaxial tensile and compressive deformations of extruded AZ31 magnesium alloy rods at different temperatures were carried out.The results show that the yielding strength is different during tensile and compressive deformations,and there is obvious asymmetry between tension and compression at different temperatures.The main reason is that the strong {0001} ED silk texture formed in the extruded AZ31 magnesium alloy rods,the tensile stress was imposed on grains along the C axes of grains is under compression along the axis of rods,and {10-12} extension twin is easily to start,but it is difficulty to start the {10-12} extension twin under the axial tension of rods,the basal and prismatic slips predominantly start.Different micro deformation mechanisms during above tensile and compressive deformation causes the asymmetry between tension and compression stress-strain curves of AZ31 magnesium alloy rods.(2)The cyclic torsion deformation test of AZ31 magnesium alloy bar specimen under different conditions was carried out.We can face that the peak stress is correspondingly raised with the increase of torsion angle at the same temperature.More extension twins formed within microstructures at boundary of the specimen compared with the center of the specimen.The peak stress was decreased with increased deformation temperature under condition of the same torsion angle.The obvious thermal effect produce during the cyclic torsion,causing the decrease of torsion stress with the increase of torsion cycles.(3)The cyclic torsion of extruded AZ31 mg alloy rod under conditions of axial tension or compression were carried out.Results show that peak stresses of stress-strain curves under axial compression were higher than the one under axial tension.Extension twin variants start irregularly,and different twin variants start during above cyclic torsion deformations.