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Multilayered sheets of AA1050 and AA7050 Al alloys produced by hot accumulative roll bonding (ARB) are tested to estimate their forming limit diagrams (FLDs). Sheets processed with preheating at 450 and 500 °C for up to six ARB cycles are submitted to Nakazima tests with an in situ digital image correlation system and tensile tests to analyze the mechanical behavior. X‐ray measurements and electron backscatter diffraction are performed to obtain the crystallographic texture and the mesotexture, respectively, and thus characterize the heterogeneous microstructure. A bimodal grain size distribution is observed in these sheets since AA7050 layers present elongated and fine grain size with nanometric precipitates and AA1050 layers present coarser and equiaxed grains. In addition, texture analysis indicates both rolling and shear components in the sheets. The FLDs show that the forming properties did not follow the expected rule of mixtures when compared with monolithic alloy sheets. Overall, the multilayered AA1050/AA7050 processed by means of ARB at 500 °C presents better formability than that at 450 °C, due to the combination of lower anisotropy measured by the Lankford coefficients r¯ values close to 1 and low normal anisotropy Δr values. [ABSTRACT FROM AUTHOR]

In this investigation, AA1050/AA7050 multilayered composite sheets were produced by Asymmetric Accumulative Roll-Bonding (AARB) in order to evaluate microstructure evolution and the interfacial zone. The asymmetric rolls introduced an extra component of shear strain, which provided conditions for necking and/or rupture in the AA7050 layers during processing at 500 °C yielding a wavy-pattern. On the other hand, at 450 °C the continuity of layers was maintained. Thus, AARB parameters can be controlled to produce wavy- or flat-pattern structures in multilayered composites. The hardening of the AA7050 layers after processing at 450 °C was caused by overaging and grain refinement, whereas at 500 °C it was due to the precipitation of η' and η-phases. The hardening of the AA1050 layers was attributed to grain refinement achieved from continuous dynamic recrystallization. In addition, diffusion bonding has a significant role in the formation of AA1050/AA7050 interfaces by the AARB process, as observed in the interdiffusion zone. Taken together, these findings provide insights into structural pattern formation and microstructural control in Al-based multilayered composites using the AARB process. Unlabelled Image • Multilayered sheets were produced by Asymmetric Accumulative Roll-Bonding (AARB). • AA7050 Al alloy constituted the hard phase and the AA1050 Al the ductile matrix. • AARB parameters can be controlled to produce wavy- or flat-pattern structures. • Temperature cycle affects the precipitation hardening of the AA7050 layer. • The hardening in the AA1050 layer is caused by cDRX and residual strains. [ABSTRACT FROM AUTHOR]

The deformation behaviour of metals and alloys is significantly affected by both stacking-fault energy and processing temperature. By lowering the former, deformation twinning is favoured over dislocation slip, whilst cryogenic processing partially suppresses dynamic recovery. Three materials having different stacking-fault energies, that is, Al AA1050 (high), pure Cu (medium) and Cu–15Zn alloy (low) were rolled at room (RTR) and at cryogenic (CR) temperatures up to a true strain equal to 1.5. Annealed coarse-grained samples were tested in tension at room and cryogenic temperatures. The processed samples were characterized by optical and transmission electron microscopy, hardness measurements and room-temperature tensile tests. CR increases the tensile strength with respect to RTR for the three materials; elongation to failure is decreased for AA1050, whilst for Cu and Cu–15Zn the CR effectively increases the ductility. Cu–15Zn sample after CR exhibits a microstructure relatively heterogeneous, suggesting static recrystallization events in the temperature excursion from 77 to 298 K. Finally, it was concluded that cryogenic deformation increases strength, whilst low SFE increases the ability to absorb plastic deformation, an effect strongly increased at cryogenic temperatures. The present investigation gives some basis for the development of cryogenic severe plastic deformation processes. [ABSTRACT FROM AUTHOR]