The Structure Evolution And Interface Strength Of Rolled Al/mg/al Three-layer Clad Sheet

As a kind of light and high-strength metal structure material,magnesium alloy has many excellent properties and abundant reserves,which show a broad application prospect in vehicle lightweight and environmental pollution reduction.However,magnesium alloy is easy to oxidize and the MgO is loose,which seriously limits the development of its application field,especially for rolled plate.Therefore,the Al/Mg/Al clad sheets can effectively improve the corrosion resistance of magnesium alloy plate by covering the aluminum layer on both sides.However,due to the reasons of oxide film and compound layer,the bonding strength of Al/Mg is difficult to improve.At present,there are many methods such as explosive bonding,cast rolling bonding,friction stir welding to realize the combination of Al/Mg interface,but they all have some disadvantages.It is still not possible to determine a kind of preparation process of aluminum-clad magnesium plate with high strength interface and large-scale production.In order to solve this problem,In this paper,the influence of first rolling,intermediate annealing,secondary rolling and low-temperature annealing on the interface structure and bonding strength of Al/Mg in the preparation process of Al/Mg/Al clad sheet is studied by using the secondary rolling method.The Al/Mg/Al clad sheet with high interface bonding strength is obtained.The results are as follows:1)First rolling is used to prepare Al/Mg/Al clad sheets,the total rolling reduction of the clad sheets should be more than 45%.When the rolling temperature is 400? and the rolling reduction rate is 53%,the best peeling strength is 3.7 N/mm2)Annealing time is more than 15 minutes,there are two kinds of intermetallic compounds,Al12Mg17 and Al3Mg2 on the interface of Al/Mg/Al clad sheets.With the increase of annealing time,the thickness of the compound layer at the interface increased,and its Vickers hardness is much higher than Al and Mg interface3)The results of peeling experiments on different stages of Al/Mg/Al clad sheet show that the peeling strength of the interface is only 3.7 N/mm in the first rolling,at this time,there is no Al element in the Mg peeled surface,and the peeling strength of the interface is only limited in the mechanical engagement;after the intermediate annealing,the peeling strength further decreases,and the peeling surface is smooth and flat,indicating that the fracture occurs at the compound layer;after the second rolling,The peel strength increased significantly from 4.5 N/mm of 15%reduction to 9.2 N/mm of 30%and 12.7 N/mm of 45%.The peel strength increased with the increase of secondary reduction4)After annealing at 100? for 4 hours,21.9%elongation and 11.9 N/mm peel strength were obtained.At this time,the metallographic structure showed that part of the twin was removed,the degree of grain homogenization was increased,and no new intermetallic compound layer was formed at the interface.