| AZ31 alloy is one of the deformation magnesium alloy used most commonly,and is used widely in sheet-rolling and extrusion profiles.AZ31 alloy is not strengthened by heat treatment,therefore,it is feasible way to improve its mechanical properties further through casting and deformation process optimization.A test of electromagnetically continuous casting (EMC) was realized in the paper by imposition of low frequency electromagnetic fields and integration design of electromagnetic continuous lubrication system,cooling system and protection systems in the mold.The effects of on structure and mechanical properties of magnesium alloy AZ31 was studied under different electromagnetic frequency,electromagnetic intensity and casting speed.By result of test,the optimized craft condition was found.In this experimental condition of V= 200mm/min and I=120A,when the electromagnetic frequency changed from 15 Hz to 30 Hz, AZ31 alloy grain refinement level and the tensile strength increased significantly,yield strength and elongation rate improved slightly.In this experimental condition of V=143mm/min and f=10Hz,when the electromagnetic field intensity is too low or too high,the organizations refinement effect not ideal;when Current strength I=60A,the organization will be better refining results,and higher hardness was received.In this experimental condition of f=30Hz and I=120A,when the electromagnetic Casting speed changed from V=200mm/min to V= 230mm/min,grain refinement extent bad and the mechanical properties has declined.Meanwhile,the effects on the microstructure and properties of magnesium alloys AZ31 were analyzed after adding grain refiner of Al-5Ti-1B and varied content of Ca and Be elements.The results show that grain refinement extent,the average yield strength and hardness increase,but the tensile strength and elongation were little changed after adding 1% (Al-5Ti-1B).The grain refinement extent,macrohardness and the yield strength improved significantly,but elongation dropped significantly after adding 2%Ca.There are a negative impact on Microstructure and mechanical properties,the grain refinement extent and plastic have become bad after adding 0.0075%Be.The AZ31 magnesium alloy has been deformed by isothermal compression under temperature 200℃～350℃and at 0.001～0.1s-1 strain rate in the experiments using Gleeble1500 thermo-simulator. Through the experiment,the curve of real stress and strain are achieved.The behaviors of flow stress and microstructure have been investigated.Dynamic recrystallization(DRX) occurred at the condition from the flow curves and optical microscopy figures.The flow curves showed a peak and a decline towards a steady-state regime which lower as temperature T rose and strain rate declined. Influence to flow stress was analysed and activation energy was gave by flow stress and microstructure. By the test it could be applied to make technology of hot working for AZ31 magnesium alloy and give elementary date for further study.Magnesium alloys AZ31 under different electromagnetic condition was selected for an extrusion tests.the microstructure and mechanical properties of AZ31 magnesium alloy before and after extrusion were investigated,and the analysis on tensile fracture surfaces of these alloys has been carried out.The influence of electromagnetic condition on the mechanical properties of as-extruded magnesium alloys is investigated.The results show that dynamic recrystallization occurred and grain has refined obviously by extrusion, therefore the mechanical properties greatly improved.The study also found that the impact of the electromagnetic frequency to the mechanical properties has genetic,the mechanical properties after extrusion have been no change.
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