Production of high strength metallic foil by accumulative roll bonding process

Aluminum foils have been extensively used in packaging and household applications to protect foods and pharmaceutical products from environmental effects. In recent years, sever plastic deformation processes have been highly regarded due to the production of ultra-fine-grained metal materials. The high applicability of nanostructures, due to their unique physical and mechanical properties, reveals the importance of investigations on new forming methods. Accumulative roll bonding (ARB) process is one of the best and most practical methods for forming metal sheets, which mechanism is the plastic deformation of material through the passage between two or more rollers. In this investigation, thin aluminum foils with a thickness of two hundred microns were produced using accumulative roll bonding method in five passes without lubricant or additional heat treatment between passes and at ambient temperature. To investigate the mechanical properties, uniaxial tensile test and microhardness test were used, and to investigate the microstructure and fracture surface area, scanning electron microscopy was used. The ultimate tensile strength at the end of the fifth ARB pass reached 393 MPa, about 5.9 times larger than of the initial sample. Also, compared to the previous research, the obtained strength was highest due to the lower thickness of the layers and the penetration of surface oxides into the metal matrix during preparation. Furthermore, by increasing the number of accumulative roll bonding passes, the thickness of the layers decreases and the bonding quality between layers is improved. Investigation on tensile fracture surface after five passes exhibits ductile failure mechanism.