Dynamic Recrystallization during Warm Accumulative Asymmetric Roll Bonding (AARB) of the AA1050 Aluminium

Abstract

In this work asymmetric accumulative roll bonding (AARB) was applied to a AA1050 aluminum up to ten cycles at 350 and 400°C. The texture was measured by x ray diffraction and EBSD. Hardness and tensile tests characterized the strain distribution and bonding efficiency. At 350 °C the microstructural refinement was stabilized after four cycles and mean grain sizes of one micron and a saturation yield strength of 160 MPa was achieved. At 400°C grain growth took place yielding a bimodal microstructure with mean grain size of 9 microns. During repeated bonding cycles recovery and dynamic recrystallization were observed and extra shear in the interfacial region yielded a fairly well homogeneous strain distribution and weak shear texture across the sheet for both temperatures. The strongest component in both cases was the rotated cube orientation. The last bonding surface was the weakest bond but adding an extra 50% reduction step to the process increased the interfacial strength considerably.