Elastic-plastic bending properties of an AZ31B magnesium alloy based on persistent tensile preloads

Compared with the mechanical properties obtained from free-standing three-point bending tests, plate-shaped structures would exhibit different bending properties when subjected to tensile preloads. In this paper, elastic-plastic bending properties and fracture modes of an extruded AZ31B magnesium alloy based on tensile preloads varying from 0 N (Mg alloy specimen is double clamped) to 350 N are investigated. Bending load-deflection curves with various tensile preloads are obtained, the maximum bending deflection, residual deflection and the ratio of residual deflection to maximum bending deflection all gradually decrease as the preload increases. The preload is verified to improve the resistance capacity to bending deformation of the alloy specimens. Progressive linearization trend and obvious nonlinearities of the loading and unloading load-deflection curves are explained, respectively. The tensile preloads promote the directional movement of neutral layer, and the increased preloads would cause more inhomogeneous stress distribution when the bending deflection reaches its maximum. Moreover, regarding the fracture modes, as the preload increases, the proportions of shear dimples and equiaxed dimples decreases, and the proportion of tear dimples gradually increases.