Details

Autor(en) / Beteiligte

• Chan, W.L.
• Fu, M.W.

Titel

Experimental studies and numerical modeling of the specimen and grain size effects on the flow stress of sheet metal in microforming

Ist Teil von

• Materials science & engineering. A, Structural materials : properties, microstructure and processing, 2011-09, Vol.528 (25-26), p.7674-7683

Ort / Verlag

Kidlington: Elsevier B.V

Erscheinungsjahr

2011

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• • Interactive effect of grain and specimen sizes on deformation behavior is studied. • The volume fraction of grain boundary changes with the specimen and grain sizes. • The flow stress decreases linearly with the ratio of specimen to grain sizes. • Flow stress decreases with the increasing volume fraction of surface grains. • Methodology to identify the surface and internal grain properties is proposed. In this research, the interactive effect of grain and specimen sizes on the flow stress of sheet metal in microforming is investigated via the tensile test of pure copper and numerical modeling. Models based on different assumptions are proposed to analyze the size effect phenomenon. It is found that the flow stress decreases linearly with the decrease of the ratio of specimen to grain sizes. The grain boundary thickness decreases and its volume fraction increases with the decrease of grain size. The variation of grain boundary thickness is not proportional to the variation of grain size. Furthermore, the fraction of grain boundary increases with the strain and the ratio of specimen to grain sizes. Based on the FE simulation, it is found that the simulated flow stress, which is modeled based on the identified grain boundary thicknesses using the proposed models, has a good agreement with the experimental result. In addition, the size effect on flow stress is also analyzed based on the surface layer model. The methodology to identify the surface and internal grain properties is proposed based on the experimental result. The identified properties are applicable in modeling of the interactive effect of specimen and grain sizes on flow stress. This research thus provides an in-depth understanding of the plastic deformation behavior in microforming process.