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Abstract
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In this paper, ambient temperature (room temperature) accumulative roll bonding (ARB) is performed on Al2024 aluminum alloys to assess grain refining phenomenon. The microstructural evaluations show reduction in the grain size from about 25 μm to about 350 nm by a factor of ∼70 upon six cycles of ARB; X-ray diffraction patterns were usedtoassesstheincreaseinthedislocationdensity.Theyield and tensile strength of the ultrafine grained Al2024 after the sixth cycle, 465 and 492 MPa, were about 650 and 186% higher than that of the as-received sample, 62 and 172 MPa, respectively. Investigating the fractured surfaces of the tensile test specimens by scanning electron microscopy showed that ARBprocessaltersthemodeoffracturesubstantially;fracture surfaceofannealedsample consistsofdeepequiaxeddimples which is an indication of ductile fracture. However, this changesintheARBedspecimenstoshearductilerupturewith shallow and small elongated dimples.
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