Microstructure And Properties Of Mg-Al-Zn Wrought Magnesium Alloys After Asynchronous Rolling And Heat Treatment

Magnesium and magnesium alloys are the lightest metal materials,it is named as the "environmental friendly metal of the 21 st century",and has many advantages performance,such as low density,high specific strength and high specific stiffness.Wrought magnesium alloy has wide application prospects in aerospace,automobile,electronic products and other fields,so it receives unprecedented attention.Magnesium alloy has hexagonal close-packed structure,plastic processing performance is poor,which will seriously restrict the development of the wrought magnesium alloy.In order to study the rolling deformation law of Mg-Al-Zn magnesium alloy,a series of studies are carried out by synchronous rolling technology,asynchronous rolling technology and heat treatment technology based on the magnesium alloy AZ31 and AZ61.The effect rolling process and heat treatment parameters on the microstructure and properties are studied,which could benefit the ultrafine grains and improved properties for magnesium alloy sheet.It has the low cost,high strength,ductility and diversified mechanical properties,and is used to application in industry.(1)The chemical composition of the AZ31 and AZ61 magnesium alloy is tested,and the influence of composition and elements on the experiment is analyzed.The 25 mm thick billet is rolled into 10 mm by the laboratory roughing experiment.The results show that the number of dynamic recrystallization gradually increases with the increase of rolling passes,and the structure is obviously refined and the hardness is improved greatly.(2)The synchronous rolling experiment of AZ31 and AZ61 magnesium alloy is carried outunder three different rolling temperatures,2mm thick billet is obtained by 9 rolling passes.The results show that the plasticity deformation ability of magnesium alloys is improved and the dynamic recrystallization process is promoted with imcreasing the rolling temperature.(3)The asynchronous rolling experiment of AZ31 and AZ61 magnesium alloy is studied considering 390?,420 and 450 rolling temperature.Through comparison ? ?and analysis microstructure and hardness of the sample for each rolling passes,it is found that the larger initial grain,a small amount of fine recrystallization grain size and a certain number of twin organizations are observed when the rolling temperature is 390?.Many layered brittleness in the second phase are found,intergranular is melted and plasticity is declined due to the rolling temperature above the eutectic temperature when the rolling temperature is 450?.The uniform fine microstructure and good mechanical properties are obtained when the rolling temperature is 420?.(4)The recrystallization annealing and artificial aging treatment of AZ31 and AZ61 magnesium are investigated.The results show that the shear zone and twin can induce recrystallization nucleation,and become the core of the recrystallized grain size,which will effectively improve microstructure and enhance comprehensive performance of magnesium alloy after rolling.