Study On Welding Technology Of Mg/Al Composite Plate

Magnesium alloys and aluminum alloys are both important light metals. Layered composites made of magnesium alloys and aluminum alloys will be of great application prospects. The best way to achieve the composite of magnesium alloy and aluminum alloy is explosive welding. The interfacial microstructure of the composite by explosive welding can influence the welding quality. So it is very important to study on the interface of the composite. During the explosive welding process, the collision of base and flyer plate can cause injury of the composite. Therefore it is necessary to anneal the composite. But at present the research on Mg/Al explosive welding is rarely reported and the subsequent heat treatment and the connection of the composite are more rarely studied.This work is to fabricate AZ31/1060 and AZ31 /5083 explosive cladding and then to research on the bonding interface of the two kinds of composite. Furthermore use AZ31/1060 composite plate as the research object and anneal the composite plate through different process. And then study on the effects of annealing on the bonding surfaces. Finally explore the friction stir welding of AZ31/1060 composite plate. Draw the following conclusions:Welding rate of AZ31/1060 can reach 99.4% and AZ31/5083 can reach 47.7%. Under the conditions of this experiment, when the distance of base and flyer plates is larger, the interface more prone to wave structure and vortices are easier to be observed at the interface and the tensile strength and shear strength are higher. Tensile strength of AZ31/1060 composite plate can reach 220 MPa, shear strength can reach 82.9MPa, In-plane bending strength can reach 499 MPa and out-of-plane bending strength can reach 368 MPa. Tensile strength of AZ31/5083 composite plate can reach 346 MPa, shear strength is up to 114.8MPa, In-plane bending strength reach 581 MPa and out-of-plane bending strength is up to 576 MPa. The deformation zones at the interface gradually disappear with the increasing of annealing temperature and holding time. After annealing, the diffusion layer appears at 1060 side near the bonding interface. When the annealing temperature is 350 ℃ and the holding time is 9h, solid solution of Al diffusing in Mg, Al12Mg17, Al3Mg2 and solid solution of Mg diffusing in Al can be found in the diffusion layer from the side of AZ31 to 1060 side. Tensile strength and shear strength of composite plate decrease with the increasing annealing temperature and holding time, while the elongation increases with the increasing annealing temperature and holding time. After annealing, the tensile strength and shear strength of AZ31/1060 composite plate are higher than the original composite plate. For AZ31/1060 composite connection, when the revolving speed of the stirring pin is 1400 r/ min and travel speed is 40mm/min, the forming quality of friction stir welding is good. In DXZ、TMAZ and HAZ, recrystallization phenomenon are observed. In DXZ the grains are fine equiaxed and Al12Mg17 intermetallic compounds disperse on the equiaxed grains in DXZ. The tensile strength of composite plate after friction stir welding is 108 MPa, elongation is 1.4%. In bending test, in-plane bending strength is 182 MPa and out-of-plane bending strength is 121 MPa.