| As the lightest metal structural material,magnesium alloy has the advantages of high specific strength,strong electromagnetic interference resistance,easy processing,degradability and recyclability.However,the special hexagonal close-packed crystal structure of magnesium alloy leads to poor plastic forming performance at room temperature,which makes the traditional processing of magnesium alloy often require heating and interpass annealing treatment,so as to make magnesium alloy have good surface quality and mechanical properties.Compared with the traditional means,the introduction of pulse current in the rolling process can effectively reduce the anisotropy of magnesium alloy and improve the mechanical properties and surface quality.Therefore,this paper introduces the pulse current into the rolling of magnesium alloy,analyzes the specific influence mechanism as the main breakthrough point,and then obtains an electroplastic rolling magnesium alloy ultra-thin strip process.Firstly,the electroplastic constitutive equation of magnesium alloy was established by comparing the electroplastic tensile and isothermal tensile of AZ31 B magnesium alloy.The experimental results show that the pulse current will have an additional effect on reducing the stress below the recrystallization temperature of the magnesium alloy.Under isothermal conditions,there will be lower tensile strength and greater elongation after fracture,which will make the magnesium alloy have better plasticity and more conducive to rolling deformation.Based on the Johnson-Cook constitutive model,the pulse current parameters are introduced to obtain the electroplastic constitutive model of magnesium alloy.Secondly,by rolling magnesium alloy with different rolling parameters and pulse current parameters,the anisotropy of mechanical properties and microstructure evolution of magnesium alloy after rolling were observed and analyzed.The experimental results show that when the pulse current intensity is too low or too high,the mechanical properties of the magnesium alloy sheet after rolling will be reduced,and there will be a large number of twins and shear bands in the microstructure.Only when the pulse current intensity is appropriate,the magnesium alloy sheet with excellent mechanical properties and uniform structure can be obtained.Finally,the rolling process parameters of electroplastic asynchronous continuous rolling of magnesium alloy without intermediate annealing were determined,and finally the magnesium alloy foil with a thickness of about 0.06 mm was obtained by the process.In order to improve the rolling efficiency and improve the surface quality of the rolled magnesium alloy sheet during the electroplastic continuous rolling experiment,the different diameter roller was introduced for asynchronous rolling.Finally,the magnesium alloy foil with good surface quality and size below 0.1 mm was obtained.Through experimental research,a mature magnesium alloy non-fire asynchronous electric continuous rolling process was finally obtained.The anisotropy of magnesium alloy after rolling deformation was explored to a certain extent,and an extremely thin magnesium foil strip was rolled.This provides a theoretical basis for the application of magnesium alloy electroplastic rolling to practice. |
