Study On Differential Temperature Asynchronous Rolling Of Magnesium Aluminum Composite Plate And Interface Bonding Strength

AZ31/6061 Mg-Al composite plate is a new type of composite material which can make full use of the characteristics of Mg-Al in the component layer.The component metal magnesium alloy has the performance advantages of low density,light weight and high specific strength,while the component metal aluminum alloy has the performance advantages of corrosion resistance,low cost and strong plasticity.Because the traditional rolling magnesium-aluminum clad plate has some disadvantages such as low interface bonding strength and uncoordinated deformation of magnesium and aluminum after rolling,and considering that the component layer has certain influence on the formability of clad plate,it is an important direction for the development of magnesium-aluminum clad plate to develop a new rolling process.This paper systematically studies the composite deformation behavior and interface bonding strength of magnesium-aluminum clad plate by single-pass differential temperature asynchronous rolling experiment and ABAQUS finite element method,and determines the magnesium-aluminum clad plate with excellent interface bonding performance,rolling process parameters and interface failure model.The research contents are as follows:(1)Based on ABAQUS software,the differential temperature asynchronous rolling simulation of Mg-Al composite plate was carried out,and the variation laws of thickness ratio,interface temperature field,interface stress-strain field and warpage degree of rolled plate of Mg-Al composite plate under different reduction ratios and thickness ratios were explored.The results showed that with the increase of reduction,the deformation of component metal Mg-Al gradually increased and approached to the reduction ratio,making Mg-Al coordinate deformation.The temperature distribution in the thickness direction of the rolling deformation zone is gradient,and the interface temperature is about 300℃at 30% reduction and about 320℃ at 60% reduction.The degree of warpage decreases with the increase of rolling reduction,and the influence of component metal thickness ratio on the warpage of sheet metal will be weakened when rolling at large reduction,and it will be flat when rolling at 60% reduction.With the increase of reduction,the strain difference between magnesium layer and aluminum layer decreases gradually,the strain distribution between the matrix and the cladding material tends to be uniform,the deformation coordination between metals is enhanced,and the bonding performance of the composite plate is improved.(2)The interface mechanical properties and microstructure of magnesium/aluminum composite plate were analyzed by tensile shear test and peeling test.The results show that the comprehensive mechanical properties of magnesium/aluminum composite plate with layer thickness ratio of 3:1 are better than those with layer thickness ratio of 2:1 and 5:1,with tensile strength of 284 MPa and elongation of 20.5%.At 40% reduction,there are cracks at the interface of Mg-Al composite,and the interface is not straight,showing a tortuous state.At 50% and 60% reduction,there are no cracks at the interface,which indicates that the interface of Mg-Al composite is highly bonded and flat.With the increase of reduction,the microstructure of magnesium layer is more uniform,and the microstructure at the interface is mainly fine dynamic recrystallization.The grains of magnesium layer far away from the bonding interface are elongated and relatively coarse,with twinning as the main mechanism.With the increase of rolling reduction,the interfacial shear strength increases.(3)Through shearing and peeling experiments of rolled composite plates,the finite element parameters of interface unit about bonding strength are obtained,and the peeling model is established based on ABAQUS and cohesion unit,and the fracture energy is obtained by inversion.The mathematical relationship between peeling strength and fracture energy is as follows y=11.8 x+4.9.(4)Based on the cohesion model,the tensile and bending experimental models of composite plates were established.Cohesive unit layers were embedded in the crack propagation area of magnesium-aluminum interface,and the failure behaviors of the interface under tensile and bending loads were simulated.The mechanical behaviors of the interface during failure and failure were studied.When the stress on the composite interface exceeded the interface bonding strength,the magnesium-aluminum composite interface would crack and delaminate.The comparison of the interface failure position and bonding strength with the simulation results showed that the model error was small,which verified the correctness of the interface model.