Abstract
High temperature deformation and fracture of the Al–Mg–Mn sheet consisting with the coarse-grained surface and the fine-grained center layers have been investigated. Such a microstructure was produced by the continuous cyclic bending (CCB) and the subsequent annealing. The elongation to failure has a peak value at 713 K at initial strain rates of 5.6×10−4 s−1 and 5.6×10−3 s−1 in both of as-received sample (0P) with fine grains and CCBent and annealed one (20P_A) with the coarse and the fine grains in spite of different microstructures. The m value decreases for 20P_A and increases for 0P with increasing temperature. However, the increase of the m value is not correspondent to the change in the elongation. Deformation mechanism is discussed with activation energy. The SEM micrographs of original surfaces of tensile specimen deformed to failure reveal that at the relatively high temperatures many cracks are formed inside the coarse grains. The features of fractured surface for the 20P_A sample reflect the coarse- and the fine-grained layers faithfully.
