Analysis Of Microstructures And Mechanical Properties Of Hot Extruded ZK60 Magnesium Alloy

Compared with the aluminium alloy,the research and development of mag-nesium alloy is not sufficient,nowadays,the production of magnesium alloy is only 1%of the aluminium alloy's.Magnesium belongs to the metal of close-packed hexagonal structure,its capacity of plastic deformation is so low,that it can be difficult to processed into board,belt,rods,profiles and so on,therefore magnesium alloy is mainly used its castings as structural materials.With the development of aerospace,automotive,defense and electronics industry,the existing magnesium alloy cannot meet the special requirements.Therefore,it is important to explore active approach of improving the mechanical properties and formability,thus to push the application of magnesium alloy and develop its performance advantages.In order to promote the magnesium industry in China,we must make great efforts to develop the magnesium and its production process.In this study,we use ZK60 magnesium alloy as the research object.ZK60 as the commercial magnesium alloy which has the highest strength,improving plastic is very important for expanding its application.We choose hot extrusion as technique to process ZK60 magnesium alloy.And we design the right hot extrusion mould, according to the mould we prepare the right ZK60 magnesium alloy blank.We extrude the ZK60 magnesium alloy under the different extrusion temperature and different extrusion ratio,research on the change of microstructure and mechanical properties of the hot extruded ZK60 magnesium alloy when it affected by extrusion temperature and extrusion ratio at the same time,and we also analyze the relationship between the microstructure and mechanical properties.The research has the following conclusions:(1) Hot extrusion in 300℃～400℃,what major happened in ZK60 magnesium alloy is dynamic recrystallization;dynamic recrystallization's formation mechanism major is continuous dynamic recrystallization;and the deformation mechanism major includes dislocation motion,grain boundary sliding and diffusion creep.(2)Selecting 310℃,340℃,360℃as hot extrusion temperature,grain relative as-cast's effective refinement,the least grain size is about 10μm,340℃is the ideal hot extrusion temperature uniformity,ZK60 magnesium alloy's organization is equality and tiny;its combination property is excellent.We choose 6.25,4,2.25 three extrusion ratio,along with the increasing extrusion ratio,the grain refinement effect increased.(3) Using the extruded ZK60 magnesium alloy to do mechanics experiments, including magnesium tensile testing and hardness testing,testing its mechanical properties.We can see that,the better the grain refinement and the organization equality,the better effect on the mechanical properties,extrude under the condition of 340℃,and the extrusion ratio is 6.25,the hardness,tensile strength and elongation of the ZK60 magnesium alloy is 75.5 HB,378MPa and 24.07%.