Research On Compressive Mechanical Behavior Of Magnesium Alloy Hollow Cylinder And Composite Cylinder

The hollow structure has been widely used in practical engineering due to its strong torsion resistance,large external torque that can withstand,and material saving.In addition,it is often difficult for a single metal to meet the requirements of comprehensive performance.Therefore,composite materials that can combine the advantages of two different metals have attracted more and more attention from researchers.This paper analyzes the mechanical properties and microstructure of the AZ31 alloy hollow cylinder with different hollow sizes along the TD,ND,and TN45 directions in the height direction,and the composite cylinder after the core of the hollow cylinder is filled with materials of different strengths such as Al,Mg,and rubber in the TD direction.The main conclusions are as follows:(1)The study of the mechanical behavior of the hollow cylinder shows that when compressed along the TD,ND and TN45 directions,the change in hollow size has almost no effect on the yield strength,but the increase in the hollow size,the elongation gradually decreases,and the 4mm hollow cylinder does not decrease due to the large number of twins produced when compressed along the TD;when compressed along TD and TN45,the work hardening rate showed a trend of first decreasing,then increasing,and then decreasing.Compression in the TN45 direction had a short rising period and the low peak.(2)The study on the twinning behavior of hollow cylinders shows that the sliding and twinning behaviors of hollow cylinders follow Schmid's law and adjacent twin pairs have good geometric coordination.The SF value and the geometric coordination factor of the twins produced by 3% compression along the TD direction and the TN45 direction was counted.The twins formed by the first and second variants of the internal and external SF values of different samples accounted for more than 70%,the m' value of most twin pairs is between 0.7 and 1.(3)Research on the mechanical behavior of composite cylinders containing fillers shows that the mixing rule can predict the yield point of composite materials.Compared with the samples filled with 7055 Al,the flow curves of the samples filled with silicone rubber and AZ31 are similar to the curve predicted by the compound rule.In addition,as the strength of the filler decreases,the volume fraction of twin gradually increases.(4)The study on the twinning behavior of composite cylinders containing fillers shows that the selection of twin variants during the compression process of composite cylinders with different filler materials follows Schmid's law and adjacent twin pairs have good geometric coordination.For example,the first and second-ranked variants with SF value form more than 70% of twins,and m' values are mainly between 0.6 and1.In addition,the rubber-filled sample has a large twin volume fraction because it has more crystal grains that have activated multiple variants.