Influence Of Pre-deformation And Notch On Deformation Behavior Of AZ31 Magnesium Alloy

Magnesium alloys have drawn great interest in recent years due to their many special advantages,for instance,low density,excellent mechanical properties,good impact resistance property and easy recycling,which makes their structural parts are extensively used in car,airplane,military defense and communication devices,etc.Nevertheless,the application of it is tremendous abstracted by the inferior briquette ability at room temperature and anisotropy as a result of the HCP crystallographic texture.Also,in practical applications,there would be a complex stress condition in the discontinuous part of components,and those parts often becomes the original of cracks and cut down there service life as well as security for use.In this work,AZ31 magnesium alloy were used for testing under pre-deformation treatment and high density pulse current annealing process.The corresponding deformation properties,changes of microstructures and notch effect of AZ31 magnesium alloy under different pre-deformation were studied.It could be very significant to study about the deformation behavior of AZ31 magnesium alloys,which could provide a theoretical foundation for the development of magnesium alloys.The results showed that the amount of twins in AZ31 magnesium alloy was increased with the pre-deformation,and the twin shape turn wider with the increase of prestrain degree.EBSD technique showed that most of the twins were {1012} twins,and only a few of them are {1011} twins.The yield strength of pre-compression samples decreased significantly,the tensile strength and elongation of the samples raised slightly with the growth of compressive pre-strain,while the tensile strength and yield strength of pre-tension samples raised obviously and the elongation reduced.The grain refining effect caused by twin boundaries is the main reason for the increase of strength.There was an obvious "notch strengthening" effect in notched AZ31 alloy specimens compared with the smooth ones.The elongation of notched samples could be improved greatly after pre-compression,while pre-tension treatment would produce opposite effects.The reason for this was mainly the reorientation produced by twinning during precompression,which would be beneficial to the subsequent stretching.However,the change of the crystal orientation of the pre-stretched samples were not obvious,crystalline slip was attributed to this plastic deformation.After the pulse current treatment,the yield strength of pre-compression AZ31 alloy samples picked up,conversely,the strength of pre-tension specimens decreased.The mechanical properties of pre-compression specimens with notch radius 3.2 mm were better than those with notch radius 0.4 mm after pulse current treatment.The basal texture were weakened after pre-deformation of different degree and pulse current treatment.Meanwhile,the occurrence of static recrystallization made the base slip and twinning easier,and the deformation ability of AZ31 magnesium alloy was improved.