Research Of The Mechanism Of Dynamic Recrystallization Induced By Electropulsing In Magnesium Alloy

Under electropulsing tension (ET) tests, the mechanical properties,fracture evolution and microstructure of AZ31Magnesium (Mg) alloy areinvestigated. The mechanism of dynamic recrystallization (DRX) induced byelectropulsing in Mg alloy is proposed. The mechanism is proved byelectropulsing deep drawing (EDD) tests.First, the elongation to failure is increased dramatically and the fracturemode is changed obviously under ET. The microstructure evolution shows thatthe improvement in plasticity of Mg alloy is the result of fine recrystallizedgrains.Second, the mechanism of DRX in Mg alloy induced by electropulsing isproposed based on the results of ET tests. In order to determine the realtemperature that DRX occurs, the method for calculating the temperatureduring ET is studied. The calculated temperatures are much lower than thoseunder conventional warm deformation. It means that DRX in Mg alloy isaccelerated significantly by electropulsing. The accelerating effect on DRX isbased on the coupling of the thermal and electromigration effects of theannihilation effect induced by electropulsing. Based on the theory of flux ofvacancies, the method for calculating the thermal effect is provided. It isindicated that due to the special heating method, the thermal effect ofelectropulsing is different from that of conventional warm deformation.Compared with the electromigration effect, the relationship between the twoeffects of the annihilation effect is discussed. Moreover, the accumulationeffect of electropulsing is proposed. On the basis of the electron wind forcetheory, the method for calculating the accumulation effect is provided and therelationship between the annihilation and accumulation effects ofelectropulsing is established. It is indicated that the relationship evolution ofthe annihilation and accumulation effects represents DRX evolution in Mg alloy, including recrystallization energy storage, DRX and grain growth.Third, the effect of electropulsing fails to show an ideal performance inEDD tests. The microstructure indicates that the occurrence of DRX is notobvious even at the temperature of conventional warm deformation. The resultcan be explained by the relationship between the annihilation andaccumulation effects under EDD. It also shows that the mechanism of DRX inMg alloy proposed is somewhat reasonable.