Effect Of Electropulsing Treatment On The Formability Of Pre-deformed AZ31B Magnesium Alloy Sheet

Global warming and resource depletion place higher demands on green development.The application of magnesium alloys is of great significance for achieving sustainable development in the automotive industry and modernization.However,poor plasticity at room temperature still restricts its application.The pulse current,acting quickly and locating accurately,can induce recovery and recrystallization of materials,which can improve the properties of magnesium alloys significantly.In this work,the effects of pre-deformation and electropulsing treatment(EPT)on the microstructure evolution and mechanical properties of commercial AZ31B magnesium alloy sheet were explored,and the effect of EPT on the formability of pre-deformed magnesium alloy sheet were also investigated.Firstly,the commercial AZ31B magnesium alloy sheet was subjected to EPT to obtain suitable parameters.It is found that the temperature of samples were suitable when current ratio is 4%and the duty cycle in 35%?20%.With the increase of amplitude current density,the flow stress decreases obviously while the elongation increases.When the amplitude current density is 24.57A/mm~2,the yield ratio reaches the minimum value of 0.341.The Erickson experiment showed that the formability is improved at 200°C.In addition,the pulse current has selective effect,which can promote the dislocation activity,thus improving the comprehensive properties of material.Secondly,the effect of pre-stretch deformation on EPT was studied.The7%was selected as the appropriate deformation amount by analyzing the temperature evolution of 4%,7%,and 10%pre-stretched samples.The influence of EPT on the anisotropy of AZ31B magnesium alloy sheet with the pre-strain of7%was further explored.When the temperature rises to 300°C,the anisotropy of the magnesium alloy decreases significantly,and the difference of yield strength in different directions decreases from 33.45 MPa to 12.19 MPa.Furthermore,the IE-value of EPT samples after pre-stretched was increased by39.9%when the temperature was 320°C.Finally,the effect of rolling deformation before EPT on the properties of the sheet was studied.The results showed that the elongations of both 0°and 90°samples are greatly increased after EPT.However,due to the different rolling routes and too large initial stress produced by rolling processes,the mechanical properties of unidirectional rolled samples and cross rolled samples show opposite trend,the anisotropy of the sheet was not effectively weakened,and the formability change little.In summary,the combination of suitable pre-deformation and EPT can significantly improve the comprehensive properties of AZ31B magnesium alloy sheet.