Study On The Roll-cladding Process Of AL1050/AZ31/AL1050

Pure aluminum/magnesium/pure aluminum clad plates were fabricated by the hot rolling method. The effects of rolling temperature, pass reduction on the interfacial bonding strength were researched; and the effect of the subsequent annealing process on the interfacial bonding strength and the joint interface structure were investigated. The bonding mechanism was discussed, and then the optimal roll cladding parameters were given.It is shown that when other conditions are same, with the increase in rolling temperature the bonding strength increase first then decrease. With the increase in pass reduction the bonding strength increases, but the checked edge occurs when the pass reduction is high. The optimal roll cladding parameters are determined as:rolling temperature is 410-430℃, pass reduction is 50-60%. At such conditions, the interfacial bonding strength is about 45-50MPa and the process property of the clad strip is good.Appropriate subsequent annealing can improve bonding strength to some extent, but brittle compound forms and the bonding strength reduces sharply if the annealing temperature is too high or the annealing time is too long. The optimal annealing parameters are determined as:annealing temperature is 250℃, annealing time is 30 minutes. The reaction phases are estimated by EPMA analysis to be Mg17Al12 in the magnesium side and Mg2Al3 in the pure aluminum side.Rolling temperature has effect on the deformation amount of each component layer, while pass reduction has little effect. With the increase in pass reduction the deformation amount of both aluminum and magnesium layer increases, but the deformation amount of magnesium layer is much greater than that of aluminum layer.Cracking mechanism and inlaying mechanism take place during roll bonding and make the initial mechanical bond. The initiation and evolution of heat effect mechanism is the main factors leading to the high bonding strength. The inter-diffusion mechanism as well as can improves bonding strength to some extent.