Papers by Keyword: Severe Plastic Deformation (SPD)

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Authors: Hiroyuki Toda, Toshiro Kobayashi
Abstract: Cutting chip is, generally, remelted for recycling solely as raw materials. In terms of microstructures, however, the cutting chip may be identified utilizable due to highly accumulated strain during its formation. In this study, aluminium chipsareconsolidated by cold severe plastic deformation so that their highly deformed microstructure is utilized for strengthening. After a preliminary investigation in which a variety of cutting processes and conditions are examined to find the optimum one for the present purpose, the aluminium chips have been successfully consolidated by a combination of pressing and swaging. The consolidated chips exhibit superior strength to a wrought alloy together with finer microstructure when compared at a same applied strain. In addition, a simple method is demonstrated effective to eliminate the undesirable effects of oxide film on the surface of the chips, which inevitably causes debonding during loading.
Authors: Kiyoshi Matsubara, Yuichi Miyahara, Koichi Makii, Z. Horita, Terence G. Langdon
Authors: Terence G. Langdon, Minoru Furukawa, Minoru Nemoto, Z. Horita
Authors: Yuji Kume, Masakazu Motohashi, Makoto Kobashi, Naoyuki Kanetake
Abstract: Compressive torsion process (CTP) which was developed by authors is effective process for grain and precipitates refinement of metallic materials with a severe plastic deformation. In the CTP, a cylindrical specimen is subjected to simultaneous compressive and torsional loading without change in its shape. However, metal flow and strain distribution in the processed specimen are not cleared, because the deformation is very large and complicated. In the present work, visualization of internal deformation of specimen processed by CTP was investigated using dual alloy etching technique. Two kinds of aluminum alloy were prepared by cutting on fan-like shape and alternately placed to a cylindrical shape. After CTPing, contrasts in the specimen were observed by polishing and etching. The internal distribution of shear strain was quantified by measuring the displacement of interface between the alloys. As a result, the visualization and quantification of internal deformation was successfully carried out using the technique. The internal strain distribution was varied not only in radial direction but also in longitudinal direction because of frictional constraint on the lateral face. A laminate contrast of the alloys observed on the vertical cross section was well related with the strain distribution in the specimen.
Authors: Yan Beygelzimer
Abstract: We present a model of severe plastic deformation of metals under the assumption of turbulence in their representative volume element. It provides simple and natural answers to a number of questions at the border between mechanics of solids and materials science.
Authors: Igor V. Alexandrov, Ruslan Valiev
Authors: A.R. Kilmametov, Ruslan Valiev, Igor V. Alexandrov
Abstract: X-ray investigations revealed that the increase in the applied pressure during high pressure torsion (HPT) of commercially pure Ti leads not only to substructure refinement with an increase of the dislocation density and microstrain level but also to an α→ ω phase transition at room temperature. The coexistence of both α and ω phases, the latter known as a high pressure phase, in the ratio approximately of 1:3 has been obtained after removal of thehigh pressure. Texture analysis of electodeposited Ni after HPT discovered a new form of crystallite orientation distribution in the nanocrystalline state. A nearly random orientation crystallite distribution has been observed unlike the “traditional” case of a shear texture forming in cubic symmetry metals. The crystallographic texture data obtained were considered as experimental evidence of the changed plastic deformation mechanisms in nanocrystalline Ni produced by HPT.
Authors: A.R. Kilmametov, Ke Zhang, Igor V. Alexandrov, R.M. Mazitov, K. Lu
Authors: Masahide Gotoh, Kazuo Kitagawa, Sergey V. Dobatkin, Yukio Hirose
Abstract: The purpose of this study is to reveal the cause of hardening of magnesium base alloys by the high pressure torsion processing (HPT) using X-ray diffraction. HPT was applied to Mg base alloys of the Mg-Sm system (2.8-5.5 mass %Sm). HPT was performed under pressure 4GPa at 20 oC and 200 oC. HPT results in significant strengthening of the Mg-Sm alloys due to the formation of sub microcrystalline structure. The dynamic recrystallization was realized through the pole figure measurement and the photograph of X-ray back scattering. The Mg supersaturated solid solution decomposition during HPT was observed by the X-ray profile analysis and the calculation of lattice constants of the Mg phase.
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