Microstructural aspects of flow localization and plastic instability

Onyewuenyi, O.A.

doi:10.1016/0036-9748(84)90420-4

Cited by 18 publications

(4 citation statements)

References 9 publications

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“…Alternative mechanisms for shear band nucleation that do not require second-phase particles include the following: (1) thermal fluctuations [131] and (2) the mutual interaction of voids and incipient shear bands. [30,32,[132][133][134] The second of these is believed to be of great importance not only for the initial nucleation of localization but also for final fracture and failure. Dodd and Atkins [116] found that some metals exhibit localization at a strain much less than expected.…”

Section: Microstructure and Theories Of Nucleationmentioning

confidence: 98%

Shear Localization: A Historical Overview

Walley¹

2007

Metall Mater Trans A

115

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This review presents a historical approach to the development of understanding of the shear localization phenomenon in materials, concentrating particularly on impact. Deformation localization under these conditions is widely referred to as adiabatic shear banding as the timescales are such that the distances heat can diffuse are small. Dimensional analysis shows that the phenomenon is ultimately intractable to linear algebraic analysis, as it is a coupled mechanical/thermal problem. However, various linear analyses from the literature are discussed along with their limitations as they shed light on the influence of various material properties. The aim of gaining understanding is to be able to engineer materials with the required localization (and hence fracture) characteristics. The most advanced analyses show that shear band widths and spacings are determined by optimizing the diffusion of heat and inertia. Because inertia is involved, the phenomenon cannot be understood simply as a materials property: geometry and structure must play a role.

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Section: Microstructure and Theories Of Nucleationmentioning

confidence: 98%

Shear Localization: A Historical Overview

Walley¹

2007

Metall Mater Trans A

115

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“…The widely accepted mechanism of ductile failure 12,14,15 is summarised into the following three key stages, namely, the void nucleation stage which may have occurred through the process of strain incompatibility and debonding between the adjacent grains; weak and hard phases; and matrix and inclusions and perhaps particle cracking. The void nucleation is followed by void growth due to plastic strain and high stress concentration.…”

Section: Introductionmentioning

confidence: 99%

Effect of strain paths and residual delta ferrite on the failure of cold rolled austenitic stainless steels, type 304L

Ahmed

Fonseca

Sherry

2013

The Journal of Strain Analysis for Engineering Design

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This study was carried out to assess the effect of strain paths and residual delta ferrite on failure characteristics of austenitic stainless steels cold rolled to 20% reduction. Optical metallography was carried out to determine grain size and quantify residual delta ferrite. Mechanical tensile tests to failure along three orthogonal directions were carried out on annealed and 20% cold rolled samples to study the effects of strain paths on mechanical properties of the material. Post-mortem scanning electron microscopy was used to study fracture surface and cross-sectional views of the failed specimens. The yield strength of material cold rolled to 20% reduction increased relative to annealed material along the rolling and transverse directions by twice as much along the normal direction. The increase in the yield strength occurred at the expense of ductility which decreased by about half in all directions. It also emerged that material loaded along rolling and transverse directions showed a gradual failure (from rupture strength), while that loaded along the normal direction exhibited a rapid failure. Correlation between ferrite morphologies on the three orthogonal planes and failure characteristics on fracture surfaces were established. The scanning electron microscopic micrographs suggest that materials loaded along transverse and rolling directions failed with characteristic features of pure ductile failure, while specimen loaded along normal direction showed mixed features of ductile and brittle failure.

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“…The microstructure of cold rolled FCC metals has been investigated many times in the last seven decades [1][2][3][4][5][6][7][8][9] by many different experimental techniques. These techniques have included surface studies using both optical metallography with etched specimens, thin foil electron microscopy, examination of X-ray line broadening, and extensive studies of the development of deformation textures.…”

Section: Introductionmentioning

confidence: 99%