Study on the Formability and Texture evolution of AA6061 Alloy Processed by Repetitive Corrugation and Straightening.

Abstract

The enhanced mechanical properties obtained by refining the grain size down to the ultrafine-grained (UFG) regime have attracted considerable attention in recent years. The severe plastic deformation (SPD) techniques allow obtaining ultrafine-grained materials. Different SPD techniques permit processing sheet shape materials such as repetitive corrugation and straightening (RCS) and accumulative roll bonding (ARB). In this study, the formability of an AA 6061-T6 processed by RCS was evaluated. The forming limit diagrams (FLD) were obtained by Nakazima tests of samples in initial condition (T6 state) and after one and two RCS cycles. The FLD curves showed that the forming capacity decreased from the first RCS cycle. Likewise, uniaxial tensile tests at different temperatures and strain rates were conducted to analyze the effect of the RCS process on the strain rate sensitivity. They showed a relatively high strain rate sensitivity coefficient in the samples after one and two RCS cycles, which indicates an improvement of i) the capacity of the material to delay the onset of the necking and ii) the formability at increasing temperatures. Finally, texture analysis was carried out employing X-ray diffraction, calculating the orientation distribution functions (ODFs). The initial texture showed a predominant cube texture component, whereas, for further RCS cycles, a weakening of the cube texture and an increment of the S texture component were observed.