فهرست مطالب ali fardi ilkhchy

In the present study, the AA 2024/AA 7072/AA 2024 multilayer composite was fabricated through an accumulative roll bonding process at 250°C. The resultant mechanical properties were evaluated after different deformation cycles at ambient temperature. It was observed that all layers were uniform and continuous during the first cycle of accumulative roll bonding. Still, after the 4th ARB cycle, AA 7072 layers were gradually necked and separated into small fragments with continuous deformation up to the 6th cycle due to lower formability compared with AA 2024 layers. After the 7th deformation cycle of ARB processing, AA 7072 fragments were distributed non-uniformly in the AA 2024 matrix. In addition, fractography analysis was conducted using scanning electron microscopy (SEM) to observe the microstructure evolution and the fracture mechanism. Also, the mechanical properties were evaluated by tensile testing and micro-hardness measurements. It was observed that hardness and tensile strength improve with increasing accumulative roll bonding cycles. Maximum tensile strength of about 389MPa was obtained after 7 cycles of accumulative roll bonding.

The Non Equal Channel Angular Pressing is one of the promising severe plastic deformation techniques which is used to produce ultra-fine grained and nanostructured materials. In the present investigation, the deformation behavior of Al1100 alloy during non-equal channel angular pressing was studied using two dimensional finite element simulation. Results showed when the ratio of the width of output to input channel is higher than 0.7, the corner gap is formed in the outer side of the intersecting area of two channels and the amount of plastic strain decreases in the lower part of the sample. In contrast, when the amount of this ratio is lower than 0.7, the dead metal zone is formed in the outer region of the intersecting area and the amount of strain is increased in the lower side of sample. It is also observed that the uniformity of the applied plastic strain is decreased with the formation of dead metal zone. In addition, the amount of damage factor is increased with increasing the ratio of the width of output to input channel and the region with higher amounts of damage factor is shifted from the lower side to the middle region of deformed sample. Finally, the results of FEM simulation showed that the amount of pressing force is decreased with increasing the width of output channel.