Effect of strain path on microstructure, deformation texture and mechanical properties of nano/ultrafine grained AA1050 processed by accumulative roll bonding (ARB)

Commercial pure Al sheets were severe plastically deformed at room temperature by accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB). Change in strain path was imposed during CARB by rotating the sheets with 90 around the normal direction axis between each cycle. Micro structural evolution of processed sheets was studied by electron back scattered diffraction (EBSD) analysis and revealed that nano/ultrafine grains (NG/UFG) with the average grain size of 380 nm and 155 nm were formed by both processing routes after eight cycles, respectively. The fraction of high angle grain boundaries and mean misorientation angle of the boundaries in the CARB were 49% and 40.20 degrees, respectively, in comparison to that of ARB sample (41% and 37.37 degrees). Deformation texture evolution demonstrated that the change in strain path leads to the formation of strong orientation along the beta-fiber. The major texture components for ARB specimens were Brass (OM < 211 > and S (123) < 634 > while those for CARB were Brass (011) < 211 > and Goss (011) < 100 >. The CARB processed specimen exhibited the tensile strength, microhardness and elongation of about 230 MPa, 92 HV and 13% compared with ARB sample (180 MPa, 80 HV and 10.5%) after eight cycles. Scanning electron microscopy (SEM) observations of tensile fracture surface of specimens revealed ductile type fracture. (C) 2016 Elsevier B.V. All rights reserved.