Study On Thermal Deformation Of AZ80+0.4%Ce Magnesium Alloy Sheet At 0 Degree Sampling Direction

The tensile behavior of the AZ80+0.4%Ce wrought magnesium alloy sheet in the direction of extrusion was studied by using a INSTRON 3382 universal material testing machine.In order to analyze the effect of deformation temperature and strain rate on thermal deformation behavior,a Arrhenius constitutive model for the thermal deformation and DMM thermal processing maps were established.SU 5000 thermal field emission scanning electron microscope was used to analyze the fracture.Finally,the critical condition of dynamic recrystallization of the alloy during high temperature drawing is determined.The microstructure evolution of the alloy during hot deformation was studied by using ZIESS PL-A662 digital optical microscope.The main results are as follows:(1)The flow stress of AZ80+0.4%Ce wrought magnesium alloy decreases with the increase of temperature,and increases with the increase of strain rate.lt presents the dynamic recrystallization rheological characteristics.Following are the Microstructure evolution law:when the deformation temperature is low,there are a large number of non crystalline coarse grains,the dynamic recrystallization is relatively complete after the temperature rises,and the grain size of dynamic recrystallization decreases with the increase of strain rate.(2)There were obvious dimples in the fracture surface,which showed obvious ductile fracture characteristics.With the decrease of deformation temperature,the number of dimples is more shallow,the number of dimples is reduced,and the number of dimples decreases.The microstructure of the fracture surface has both transgranular and intergranular cracks.(3)The Arrhenius constitutive model of flow stress of AZ80+0.4%Ce magnesium alloy are as follows:Zener-Hollomo parameter:The function of Z parameter to represent the flow stress:(4)Through the analysis of the thermal processing map of AZ80+0.4%Ce wrought magnesium alloy,the optimal deformation zone of the alloy in the deformation temperature of 380?,the strain rate of 0.00067s-1-0.0067s-1.In the region,as the material can achieve the best microstructure provides theoretical support in the process of deformation.(5)Based on the analysis of the ?-? curve,the critical condition of dynamic recrystallization of the alloy was obtained,and the critical strain of dynamic recrystallization was concentrated in the peak strain of 40%-60%.The critical stress and critical strain increases with the increase of strain rate and decreases with the increase of deformation temperature.(6)The mechanism of dynamic recrystallization varies with the deformation temperature.Twin dynamic recrystallization occurs at 300?.With the increase of temperature,the dynamic recrystallization mechanism is changed into continuous dynamic recrystallization.When the temperature rises to 420?,the dynamic recrystallization of the alloy mainly depends on the bulging Mechanism.