Effect Of Pre-deformation On Mechanical Behavior Of AZ31 Magnesium Alloy

In this paper,the rolling state AZ31 B magnesium alloy is used as the research object with different pre-strain,and the partially compressed sample is annealed.Studying the effect of pre-compression of magnesium alloy on the mechanical properties of AZ31 B magnesium alloy at room temperature by means of optical microscopy(OM),electron backscatter diffraction(EBSD),X ray diffraction analysis(XRD)and other testing methods.The main conclusions of this study are as follows:(1)Under the same strain rate loading condition,the yield strength of the material is improved after the pre-deformation,but the compressive strength decreases with the increase of pre-stress.Compared with the original un-deformed alloy,O nly 6% of the samples for pre-compression not only improves the yield strength of the material,but also the compressive strength of the material is basically the same as that of the initial sample.(2)Compared with the two time compression stress-strain diagram before and after annealing,it is known that no matter is quasi static compression or high strain rate compression,6% of the pre-compressed samples are compressed again after annealing.The yield strength increases without decreasing.Show obvious annealing intensification.Under this condition,the strongest direction of material's texture has been deflected to TD direction.The effect of annealing strengthening and texture strengthening on yield strength of materials is much larger than that caused by dislocation.When the pre compression is more than 10%,The main factors that affect the mechanical properties of materials are texture reinforcement.(3)Annealing at different temperatures was carried on pre-compressed samples.The results revealed that the dislocation density in cold deformed metal can not only be reduced after annealing of 140°C for 30 min but also maintain twin structures formed by pre-deformation.(4)Unidirectional compression of different pre-strain along TD(transverse)was conducted on rolled AZ31 magnesium alloy,We found a large number of lentoid {10(?)2}tensile twinning inside the material,and most twin parallel with each other.Compared to the original material it was found optimal distribution appear on the(0002)basal plane and(10(?)0)cylindrical plane after pre-compression.The {10(?)2} tensile twinning makes the crystallographic lattice re-orientation of 86°,the c axis of grain is parallel to the direction of compression.When the pre-compression is 6%,pre-compression sample has appeared a large number of {10(?)2} tensile twinning.But most of the twins have grown up and engulfed the original matrix grains at this time.In the pre-compression process from 6% to 14%,the number of twinning decreases with the increase of strain rate.The main type of twinning is {10(?)2} tensile twinning in the plastic deformation,10% of pre-compressed samples found a small amount of {10(?)0} compression twinning.