| Laminated metal composite of Al/Mg/Al has combined the low density,high specific strength and good shock resistance of magnesium alloy and high corrosion resistance,low cost of aluminum alloy.By using it,energy resources are saved and the weight decreased, which broadens the application prospect in aerospace field.Aluminum alloy 7075 and Mg-12Gd-3Y are studied.By analysis of high temperature rheological mechanical performance with a thermal simulator of Gleeble-1500,processing maps of different dependent variables on temperature and strain rate are drawn and the optimum machining region is thus determined.Laminated metal composite of Al/Mg/Al is prepared by hot rolling compounding.The optimum process is found by analyzing shear strength and tensile strength of composite plates with different temperatures and rolling reduction ratio.And the optimum annealing temperature and keeping time are set by interface analysis and measurement of shear strength after annealing.The results are as follows:Aluminum alloy 7075 and Mg-12Gd-3Y have steady flow when it deforms under high temperature compression.Flow stress decreases with the rise of temperature and the decrease of strain rate.The high temperature deformation of Aluminum alloy 7075 and Mg-12Gd-3Y is controlled by thermal activation.Steady flow stress can be described with an equation of Zener-hollomon parameter.Aluminum alloy 7075 should be processed at 450～475℃,with the strain rate between 0.01～20 s-1,while Mg-12Gd-3Y should be processed at 450～500℃,under the strain rate between 0.01～0.1 s-1 and 5～20 s-1.Generally speaking,rolling speed of rolling mill is corresponded to the high strain rate field,the processing region of composite rolling is therefore primarily determined as 450～475℃and 5～20 s-1.In this paper,an optimum process is set for laminated metal composite of Al/Mg/Al preparing,which are of polished surface with steel brush,end riveting applying for connecting,a composition of big outer sheet of 7075 Al alloys with smaller internal sheet of Mg-12Gd-3Y.In the optimum process,the rolling temperature is 465℃,with 0.5h keeping time before rolling,the reduction ratio of roll-bonding is 50%,and an annealing at 350℃for 2h is used after rolling for solid diffusion.The best composite quality and an optimum comprehensive performance of Al/Mg/Al composite plates are obtained by such processing. |
