Study On Preparation And Impact Resistance Of Mg/Al Composite Plate

With the progress of science and technology,the requirements of instruments and equipment on materials are more and more stringent.Therefore it has become an inevitable trend for materials to develop in the direction of multi-function and multi-structure.As a green engineering material in the 21 st century,magnesium alloy has attracted wide attention in all walks of life because of its light weight,high strength.However,the shortcomings of easy corrosion and poor plasticity seriously restrict the application range of magnesium alloy.If the aluminium alloy with good deformation ability and corrosion resistance is rolled and compounded with magnesium alloy,the composite plate with the advantages of both will greatly broaden the application range of magnesium and aluminium alloy.In this paper,it mainly focuses on the preparation of composite plate and its impact resistance.First of all,in order to obtain the Mg/Al corrugated circular composite plate with 80 mm diameter and corresponding mass of 21 g,the Mg/Al corrugated composite plate with different layer thickness ratio was tested under different rolling reduction ratio,and the Mg/Al corrugated composite plate with strong bonding interface and excellent shape was successfully prepared.The thickness of the blank for the preparation of Mg/Al corrugated composite plate and the reasonable rolling process were determined.The planar Mg/Al composite plates with the equal thickness were prepared by the same process.The microstructure of magnesium alloy side of two kinds of composite plates were characterized.It was found that the microstructure showed different characteristics in different regions along the thickness direction.For the planar composite plate,the area about 0.35 mm from the surface of the magnesium plate is mainly composed of fine dynamic recrystallized grains,and the other areas are composed of fine grains,twins and deformed grains.In addition,adiabatic shear phenomenon occured near the bonding interface.For the corrugated composite plate,the area corresponding to the wave peak near the bonding interface is mainly composed of deformed grains,and the area corresponding to the wave waist is mainly composed of deformed grains,twins and fine grains,the area corresponding to the wave trough is composed of crisscrossed twin layers.Secondly,the light gas gun device was used to conduct impact tests on composite plates and single-layer magnesium and aluminum alloy plates of equal thickness under different projectile speeds.The impact resistance performance,damage modes and energy absorption mechanisms of the four kinds of target plates were studied and compared.The results show that the impact resistance of aluminium alloy plate is the best,that of composite plate is the second,and that of magnesium alloy plate is the worst.When the impact velocity is lower than the ballistic limit speed,the impact resistance of corrugated composite plate is better than that of planar composite plate.The main damage modes of the composite plate are local plastic deformation,bonding interface delamination,plug and crack propagation at the plug mouth.Except for interface delamination,the damage mode of single-layer magnesium and aluminium alloy plates is basically the same as that of composite plates.The energy absorption mechanism of the target plate is mainly elastic-plastic deformation energy dissipation,crack initiation and propagation energy dissipation and friction energy dissipation between the projectile and the target plate.Finally,the simulation models of two kinds of composite plates under 140m/s impact velocity are established by using ABAQUS finite element software,and the deformation and damage process of composite plates subjected to hemispherical head bullet impact are analyzed in detail.The simulation results show that the target mainly goes through three stages: elasticplastic deformation,crack initiation and propagation,and final plug failure.In the process of impact,the plastic deformation of aluminium alloy layer of planar composite plate shows obvious inhomogeneity,while that of corrugated composite plate is relatively uniform.In addition,the plugging mechanism of the target plate is different.The plugging of aluminium alloy layer of planar composite plate is mainly caused by compressive stress and tensile stress,while that of magnesium alloy layer is mainly caused by shear stress.The aluminium alloy layer of corrugated composite plate is plugged under the action of shear,and the magnesium alloy layer is plugged under the action of bending.