Deformation behavior of a magnesium alloy sheet with random crystallographic orientations under various loading paths
Keywords:cast magnesium alloy, crystal plasticity finite-element method, twinning, detwinning, yield locus, unloading, contour of plastic work
This paper reports deformation behavior under various loading paths at room temperature of a magnesium alloy sheet with random crystallographic orientations both experimentally and numerically. The flow stress under uniaxial tension was larger than that of uniaxial compression. When the sheet was subjected to reverse loading, a slightly sigmoidal curve occurred under compression followed by tension, whereas it did not occur under tension followed by compression. These results demonstrated that the sample showed a tension-compression asymmetry and a strain-path dependency as in the case of rolled Magnesium alloy sheets with strong basal texture. Results of crystal plasticity finite-element simulation depicted that these characteristics occurred because of a tension-compression asymmetry in twinning activity even in the sheet with random crystallographic orientations. These results exhibited that a tension-compression asymmetry and a strain-path dependency were inevitable in the deformation of magnesium alloys at room temperature irrespective of initial textures. An evolution of contour of plastic work was also investigated numerically to support this conclusion.
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