Comprehensive procedure for the design of rolling schedules for roll bonding

摘要

Roll bonding, as shown in Fig. 1 (a), is a joiningby- forming process to permanently join two or more layers of different materials by cold or hot rolling. The process is able to produce laminated materials with a customized combination of properties. For example, for aircraft applications the high strength structural material AA2024 is cladded with pure aluminium to improve the corrosion resistance. In order to establish bonding between the different layers, an initially stacked package is heated up to the required temperature and rolled according to a rolling schedule. During rolling, metallic bonds between the layers can be formed by extruding virgin material through fractures in the passivating oxide layer induced by the elongation of the package. Therefore, high pressure and plastic deformation are mandatory. However, at the exit of the roll gap (near point B), combined tensile and shear stresses occur (see Fig. 1 (b)). These stresses are depending on the package geometry, height reduction as well as other factors and can trigger failure of the freshly established bonds. Hence, only partially bonded or even completely un-bonded packages would be produced [1].