Deformation asymmetry of AZ31 wrought magnesium alloy

摘要

In this work, the mechanical behaviour of an AZ31 wrought magnesium alloy due to tensile, compressive and four-point bending tests was analysed. Several specimens of this material were taken in different directions from a rolled plate. Tensile and compression tests allowed to characterise the mechanical properties of the material in the rolling and cross rolling directions. To take the effect of the anisotropy induced by the rolling procedure itself into account, the bending tests were carried out using specimens with four different orientations. Six strain gages per specimen allowed to observe the evolution of the strain with the bending moment during the tests. All bending specimens were bent until a total compressive deformation of 2.5%. It was observed that the corresponding tensile strain was significant lower and slightly different for each orientation of the specimens. In addition, a characteristic non-uniform distribution of deformation twinning was observed. The induced residual stresses after bending were characterised by X-ray diffraction (XRD) and incremental bole-drilling (IHD). Due to the different mechanical behaviour in tension and compression, an asymmetric residual stress distribution after bending could be observed. The neutral axis was, in all cases, shifted towards the tensile side. This observation agrees with the strain measurements during bending tests. In addition, an example of the influence of the asymmetric deformation behaviour during fatigue was given.