Effect of two-step annealing on recrystallized structure and mechanical properties in AA7075/AA1100 laminated metal composites processed by accumulative roll bonding

Abstract

AA7075/AA1100 laminated metal composites (LMCs) were successfully produced by accumulative roll bonding (ARB). Also, to investigate the effect of annealing on mechanical properties and microstructure evolution, the composites were subject to annealing treatment at three different temperature (200, 300 and 400 °C) for 1 h. The microstructure evolution was evaluated by scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS) and electron back scatter diffraction (EBSD). Tensile tests were performed to measure the mechanical properties of composites. It was observed that elemental diffusion occurred in the constituent layer interfaces, indicating that superior bonding was achieved between the layers with annealing temperature increased. By increasing the annealing temperature, the presentation of a relatively strong {100}<001>Cube recrystallization textures has been attributed to strain-induced boundary migration (SIBM) caused by a preference for the Cube-oriented grains to grow into adjacent S-oriented grains with higher stored energy. In addition, the effect of pre-recovery on anisotropy was discussed in detail. Tensile tests revealed that the plane anisotropy after the two-step annealing (TSA) process was evidently diminished in compare with the single annealing (SSA) process due to the reduced Cube texture strength and the formation of equiaxed crystal structures.