Evaluation of Micro Plastic Characteristic of Metals by Micro Indentation for Precise Analysis on Metal Forming

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The purposes of this study are development of evaluating micro plastic characteristic by micro indentation and establishment of precise analysis on metal forming. As an evaluation method of micro plastic characteristic, the micro indentation tests are conducted for aluminum alloys, steels, copper alloys and magnesium alloys to evaluate the micro characteristic of crystal grain unit. As a result, hardness of each grain has a good correlation with variation in flow stress. In addition, a finite element(FE) model considering material inhomogeneity is developed to investigate the physical meaning of micro plastic characteristic. As a result, the material inhomogeneity as a micro plastic characteristic can be evaluated successfully by micro indentation test, uni-axial tensile test and simulation results. Furthermore, the free surface roughening behavior which cannot be expressed by uniform FE model can be predicted successfully by inhomogeneous FE model under axial stress state. Consequently, precise analysis on metal forming can be realized by these results.