Refinement and control of the metal structure elements by plastic deformation

Korbel, A.; Bochniak, W.

doi:10.1016/j.scriptamat.2004.06.020

Cited by 77 publications

(44 citation statements)

References 6 publications

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“…This observation explains the strong tendency that shear bands evidence towards the rectilinear propagation for long (compared with their thickness) distances (e.g. Korbel & Bochniak 2004;Bei et al 2006). Moreover, the focusing of incremental deformation and the stress singularity strongly promotes shear band growth.…”

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confidence: 78%

The unrestrainable growth of a shear band in a prestressed material

Bigoni

Corso

2008

Proc. R. Soc. A.

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A weak line inclusion model in a nonlinear elastic solid is proposed to analytically quantify and investigate, for the first time, the stress state and growth conditions of a finite-length shear band in a ductile prestressed metallic material. The deformation is shown to become highly focused and aligned coaxial to the shear band-a finding that provides justification for the experimentally observed strong tendency towards rectilinear propagation-and the energy release rate to blow up to infinity, for incremental loading occurring when the prestress approaches the elliptic boundary. It is concluded that the propagation becomes 'unrestrainable', a result substantiating the experimental observation that shear bands are the preferential near-failure deformation modes.

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confidence: 78%

The unrestrainable growth of a shear band in a prestressed material

Bigoni

Corso

2008

Proc. R. Soc. A.

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“…[50] KOBO guarantees highly fragmented and homogeneous structure of products. [51,52] It consists of inducing cyclic changes of the deformation path in material being subjected to deformation as a result of the cyclic change of the straining scheme. Consequently, there is a permanent destabilization of the structure and the dominance of localized plastic flow in the intersecting shear bands.…”

Section: Kobo Methodsmentioning

confidence: 99%

Visco-Plastic Flow of Metal in Dynamic Conditions of Complex Strain Scheme

Korbel

Bochniak

Ostachowski

et al. 2011

Metall Mater Trans A

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The article applies to a piece of research inspired by the new technology of plastic metal forming called the KOBO method, which uses the mechanical and structural effects of cyclic changes of deformation path. Its commercial usage in the field of large plastic deformations, especially for the production of extruded elements made of hardly deformable metal alloys, naturally generated a question about the optimal conditions for carrying out the process and the criteria for their establishment, i.e., constitutive description. In this context, the work provides data on the force and energy consumption of aluminum and 7075 aluminum alloy extrusion processes, carried out using the KOBO method, and their dependence on the strain rate and temperature. The mechanism of deformation occurring during extrusion by the KOBO method was identified as visco-plastic flow. Characteristic parameters of the process, such as viscosity coefficiency, activation energy, activated volume, and the concentration of point defects generated during the process were evaluated.

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“…In fact, in recent years, a growing interest is observed in metal forming processes assisted by cyclic loading. The so-called KOBO-type forming proposed by Korbel and Bochniak [9][10][11][12]47] and applied to extrusion of tubes and wires has demonstrated essential advantages with respect to classical forming processes. The significant reduction of required load, growth of ductility, fine grain structure are main beneficial factors, cf.…”

Section: Introductionmentioning

confidence: 99%

Constitutive modeling of cyclic deformation of metals under strain controlled axial extension and cyclic torsion

Mróz

Maciejewski

2017

Acta Mech

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The present work provides a formulation of a constitutive model for metals with the aim to simulate cyclic deformation under axial extension or compression assisted by cyclic torsional (or shearing) straining of specified amplitude and frequency. Such a mode of deformation was recently implemented in technological processes such as extrusion, forging and rolling, cf. Bochniak and Korbel (Eng Trans 47:351-367, 1999, J Mater Process Technol 134:120-134, 2003, Philos Mag 93:1883-1913, 2013, Mater Sci Technol 16:664-674, 2000. The constitutive model accounting for combined hardening (isotropic-kinematic) with both hardening and recovery effects is presented and calibrated for several materials: pure copper, aluminum alloy (2024), and austenitic steel. The experimental data are used to specify model parameters of materials tested, and next the cyclic response for different shear strain amplitudes is predicted and confronted with empirical data. The constitutive model is developed in order to simulate technological processes assisted by cyclic deformation.

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Refinement and control of the metal structure elements by plastic deformation

Cited by 77 publications

References 6 publications

The unrestrainable growth of a shear band in a prestressed material

The unrestrainable growth of a shear band in a prestressed material

Visco-Plastic Flow of Metal in Dynamic Conditions of Complex Strain Scheme

Constitutive modeling of cyclic deformation of metals under strain controlled axial extension and cyclic torsion

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