Experimental And Numerical Investigation On The Warm Deep Drawing Performance Of Al/Mg/Al Metal Laminated Sheet

Due to the lightweight,good vibration damping and other excellent properties of magnesium alloys,they have attracted wide attention in the weight reduction fields of structure.However,poor corrosion resistance and low plasticity at room temperature limit their application in lightweight.On account of that,it is performed that superimposing a corrosion-resistant aluminum alloy layer on the surface of the magnesium alloy to develop an Al/Mg/Al laminated structure to protect the magnesium alloy from corrosion and exert their comprehensive advantages.In this paper,Al/Mg/Al laminated sheets were prepared using 5052 aluminum alloy sheet and AZ31 magnesium alloy sheet,but no atom-level connections were formed between the component sheets to avoid introducing aluminum-magnesium brittle compounds.And in the wake of that,the formability of Al/Mg/Al laminated sheet was investigated using deep drawing forming,to provide technical basis for its actual production process.First of all,this paper considers the influence of forming temperature,blank holder force,type of lubricant and drawing speed on the sheet forming,and determine the drawing height and the maximum punch force as formability indexes,then the orthogonal experiment is designed and implemented to obtain the primary and secondary order of the effect of the factors on indexes and the optimal combination of process level.As a result,for the drawing height,the order of that is the lubricant,drawing speed,forming temperature and blank holder force.For the maximum drawing force,the order of that is the forming temperature,drawing speed,blank holder force,and lubricant.The actually optimal combination of the process levels is the forming temperature of 230^oC,blank holder force of 13.9kN,PTFE grease as lubricant,and drawing speed of10mm·min^-1.Then,based on the optimal combination of process levels,the influences of the initial diameter of blank,the volume fraction of the aluminum sheet as the component sheet,the stacking direction of the middle magnesium sheet on the punch force,the change in wall thickness and so on were studied.Moreover,the forming behaviour in the deep drawing was also analyzed.The results show that the punch force increases with the increase of the initial diameter of blank,and the maximum punch force increases linearly.Increasing the volume fraction of the Al layer as the component makes the punch force increase,and introduces the ironing for wrinkling and the friction for ears caused by the drawing tools;in addition,it also increases the thickness thinning ratio of laminated sheet,and promotes the flow of the component material along the radial direction（RD）of the drawn cup,thereby that benefits to improve the height of the laminated sheet,meanwhile lessens its thickening tendency.The stacking direction of the middle Mg layer has no significant effect on the variation of the punch force of the laminated sheet;in order to avoid the risk of cracking of the outer layer and ensure better forming performance,the blank should use the laminated sheet in which the middle Mg layer is stacked at 45^o with respect to RD of skin sheet.In terms of forming behavior,the punch force reaches the maximum when the specific value between outside diameter of the flange and the initial diameter of blank is 0.875;the second fluctuation of the punch force-displacement curve results from the thickening and wrinkling of the flange constrained by the clearance between the punch and die;the third fluctuation may be caused by the friction between the ears and the mold at the end of the forming.This was confirmed in subsequent numerical simulation.DYNAFORM finite element simulation software was used to simulate the deep drawing process of three-layer laminated sheet.The simulation results show that the maximum punch force increases linearly with increase of the initial diameter of blank,which is consistent with the experimental result.In addition,the forming result of experiment is in good agreement with that of the simulation at individual drawing stage.