Manipulation of strength and ductility of AA5182-O through cyclic bending under tension and annealing processing

Abstract

Aluminum alloy (AA) 5182-O sheets are processed by continuous bending under tension (CBT) followed by heat treatment to investigate microstructural changes for optimizing strength and ductility of the alloy. Bending depth and pull speed parameters of the CBT process are optimized to enhance the achievable strain beyond a conventional uniaxial tension, by inducing significant microstructural changes in the sheets. CBT processed samples are subsequently heat treated at various time-temperature regimes to determine the best recovery condition. The combination of CBT and heat treatment effect on the mechanical properties is examined by the subsequent uniaxial tension experiment. Measured microstructural changes in terms of grain structure and texture by electron backscattered diffraction (EBSD) show that it is possible to change a 〈001〉 cube texture typically present in rolled and annealed AA sheets into a 〈111〉 fiber texture by combining CBT and annealing processing. Moreover, measured mechanical responses reveal that a particular combination of CBT and heat treatment at 270 °C for 2 h can increase strength by over 75 % at the expense of 37 % reduction of uniform ductility. Interestingly, only a complete recrystallization after CBT restores the r-value of as-received material, while the intermediate heat treatment conditions lower the r-value.