Effect Of Extrusion Process And Annealing Treatment On Mechanical Properties And Damping Capacity Of ZK01 Alloy

In general, while a magnesium alloy has the good damping performance, its mechanical property is not good, which restricts its wide applications. However, magnesium alloy has the irreplaceable superiority in many fields which require high specific strength, high specific stiffness, and high damping capacity materials. Therefore, developing a technology to improve both the damping capacity and the mechanical properties of magnesium alloy and expanding its application prospect in the military and civic industries becomes one of urgent demands.In this paper, because of its good damping capacity, as-cast Mg-0.4Zn-0.6Zr(ZK01) alloy was taken as the test alloy and extruded into samples and then annealed. First, the effects of extrusion ratio and extrusion temperature on the microstructure, mechanical properties and damping capacity of ZK01 alloy were studied by metallographic microscope, x-ray diffraction(XRD) and dynamic thermal mechanical analyzer (DMA).The relationship between the grain refinement and the damping mechanism were also discussed. Second, the effects of annealing time and annealing temperature on the microstructure, mechanical properties and damping capacity of ZK01 alloy were investigated, the process parameters of extrusion and annealing were optimized. Third, the effects of grain orientation and texture on the damping capacity of ZK01 alloy were investigated by a new sampling method, and the influence mechanism was discussed.The research results indicated that the grains of the ZK0l alloy was obviously refined by the hot extrusion process, and the ultimate tensile strength of the alloy was enhanced from 172.8Mpa to 264.9Mpa, the yield strength enhanced from 52.80Mpa to 222.06Mpa, while the elongation actually suddenly reduced from 29.08% to 14.9%. With the elevation of the extrusion temperature and the reduction of the extrusion ratio, the ultimate tensile strength and the yield strength of the as-extruded alloy assumed the declining trend, but were still higher than those of the as-cast alloy; while the elongation tends to increase oppositely. After extrusion, the damping performance of the ZK01 alloy reduced quickly, both of the extrusion ratio and extrusion temperature had influence on it; Totally the alloy extruded under higher extrusion temperature and lower extrusion ratio would have higher damping capacity.After the annealing treatments, the ultimate tensile strength and the yield strength of the extruded ZK01 alloy decreased gradually, but the elongation increased. Compared with the as-extruded condition, the damping capacity of the alloy was improved by the annealing treatment, but still lower than that of the as-cast alloy. The strength of the alloy reduced but the damping enhanced with annealing temperature's elevation and annealing time's extension. The effects of annealing process on the damping capacity of the extruded ZK01 alloy would be more remarkable when the extrusion temperature was lower and extrusion ratio was higher.The grain orientation and texture had obviously effects on the damping capacity of wrought ZK01 alloy. After rolled, the specimens which have the included angles relationship of 0°,45°and 90°with the rolling plane have different damping capacities under high strain amplitude. The damping capacities of the different specimens are as follows: A(0°)>D(45°)>C(90°). The higher damping capacity can be ascribe to the higher dislocation slip possibility on the basal plane (0001) in grains.