The effect of annealing on the formability of aluminum 1200 after accumulative roll bonding

Ultra-fine grained (UFG) materials with Nano-size structure could be produced by severe plastic deformation. Accumulative roll-bonding (ARB) as a severe plastic deformation method is a suitable method with practical applications to produce ultra-fine grained sheets and to enhance the mechanical properties. In this research, samples of aluminum AA1200 have been used for accumulative roll-bonding up to 64 layers to produce sheets with fine and homogenous microstructure. Microstructure and mechanical properties of ARB-ed Sheets with 2, 4, 8, 16, 32 and 64 layers have been investigated experimentally. Also, ARB-ed sheets formability has been studied analytically using an M-K model, experimentally by FLD tests and numerically using finite element software. It has been observed that hardness and tensile properties enhanced and more homogenous structure with ultra-fine grains were achieved especially after the fourth cycle of roll-bonding while formability showed a decrease. By annealing the samples after ARB for 30 min at 250 °C, more homogenous structure with higher formability was obtained and hardness and strength slightly decreased. This homogenous microstructure and higher formability could be attributed to recrystallization and growth of grains and also dissolving the brittle intermetallic oxides at the interface between the layers as a result of annealing after ARB. A proper balance between strength, ductility, and formability was achieved for the AA1200 alloy by annealing, which has led to an appropriate formability at the end. Finally it was observed that the annealing process increased the ductility and formability of UFG AA1200.