Research On Optimization Of Extrusion And Drawing Process Of Pure Magnesium Wire And Influences On Biological Corrosion

Magnesium has wide application prospect because of its good properties such as high stiffness/density and strength/density ratio, excellent capacities of heat dissipation, damping and electromagnetic shielding. However, due to magnesium has poor workability at room temperature, it is difficult to get pure magnesium wire by drawing process. Compared with casting magnesium, the organization of pure magnesium produced by drawing is more detailed, and have higher strength, better ductility, more diverse mechanical properties. Due to the poor corrosion rates, magnesium alloys are promising in degradable prosthetic implants.Consider for these characteristics of magnesium, there are some studies about extrusion and drawing process of pure magnesium wires and the corrosion in simulated body fluid in this paper. The extrusion and drawing process is based on previous studies, further analysis the influences of extrusion temperature on the microstructure and mechanical properties in wires drawing, and get the best extrusion process for follow-up drawing was established. Meanwhile, improvemented the annealing temperature and annealing time ,and get the best drawing-annealing process. Analyzed of evolution of the microstructure and changes of the mechanical properties in drawing. In addition, analyzed of the influences of the chemical composition , concentration, pH and grain size on corrosion of pure magnesium wire in simulated body fluid.By the study of drawing–annealing process, at the extrusion temperature of 100℃or 150℃, the mechanical properties of wires was significantly higher than it at the room temperature and the temperature of 200℃. Meanwhile, the tensile strength of drawing is higher than annealed wire. When the temperature of extrusion is high, deformation twins have more important in the coordination of dominance. Grain refinement can improve the strength and hardness of wires.By the study of corrosion tests, the corrosion of pure magnesium is related to the chemical compsition and concentration of the biological environment. In Hank's artificial simulated body fluid, the corrosion rate was slow, but its became faster in the saline. And increasing of the concentration can accelerate the corrosion rate. Grain refinement can slow down the rate., The corrosion on she surface of wire is pitting, and the extent of corrosion and the size of the pits are related to the chemical composition and concentration. of body fluid.