| Because of its light weight and material saving,thin-walled structure can effectively reduce the weight of the whole structure and realize light weight,which has been widely concerned and applied.Due to its advantages of light weight,high specific strength,high specific stiffness and easy recycling,magnesium alloy has become an important material to realize lightweight.However,the poor room temperature formability of thin-walled magnesium alloy sheet seriously restricts its industrial applications.Pulse current auxiliary forming has the characteristics of high efficiency,energy saving,and can effectively improve magnesium alloy such as difficult to forming of metal plastic forming performance,improve the quality of magnesium alloy surface shaping,promote the application of magnesium alloy thin sheet forming technology,is a new forming technology has important engineering value.In this paper,the pulsed current assisted sheet metal forming process was used to study the effect of pulsed current on the tensile and bending of AZ31B magnesium alloy sheet metal.Different pulse load current method(continuous loading with discontinuous loading)experiment,studies the pulse current loading ways of the different effect on the deformation of magnesium alloy sheet,to reveal the mechanism of electrically induced plasticity effect and study the different duty ratio,loading time of pulse current on the tensile and bending deformation behavior and the effect of eventually determine the appropriate process parameters.In this paper,AZ31B magnesium alloy was used as the experimental material,and unidirectional pulse-current-assisted tensile experiment was carried out by means of programmable ctnp-12/2000(6000)FN intelligent pulse power supply and UTM4304 electronic universal experiment,and experiments were conducted on different pulse current loading modes.It is found that under the condition of tensile stress,the intermittent pulse current is more conducive to the plastic improvement of magnesium alloy plate than the continuous pulse current;the influence of different duty cycle and pulse current loading time on the deformation behavior of unidirectional tension is analyzed,and it is found that in the duty cycle When the time of pulse current loading is 9s,the elongation reaches 40.49%,which is 44.61%higher than that of non electric stretching,and the plasticity is obviously improved.Based on the analysis of corresponding change of temperature field,it is found that under the action of pulse current,the temperature distribution of the sample is likely to be uneven,which leads to uneven strain distribution.Based on the analysis of microstructure,it is found that pulse current can also promote dynamic recombination The occurrence of crystal is beneficial to get fine and uniform grains.Pulse current assisted bending was performed by making a cylinder and a V mold.The average current density of 8A/mm~2 is the same as that of tension.The continuous loading pulse current sample is heated and easy to be perforated,and the surface forming quality is poor.While the intermittent loading pulse current can effectively control the temperature,and the forming quality of sheet metal is good.Intermittent loading pulse current,duty cycle and pulse current loading time have a great influence on the springback of the plate.When the duty cycle is 40%and the pulse current loading time is 9s,the bending in the cylindrical mold is the preferred current parameter.When v-shaped bending,the duty cycle is 40%and the pulse current loading time is 7s,which are the better current parameters,and the bending forming parts with small rebound and good surface quality are obtained. |
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