Shear bands evolution in ultrafine-grained aluminium under cyclic loading

Malekjani, Shokoufeh; Hodgson, Peter; Stanford, Nicole; Hilditch, Tim

doi:10.1016/j.scriptamat.2013.02.001

Cited by 20 publications

(7 citation statements)

References 12 publications

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“…Also, some researchers reported structural instability due to fatigue loading by an increasing grain size during fatigue tests . Moreover, creation of bigger shear bands due to a combination of the micro shear bands, which were created owing to intertwined dislocations, and local aggregation of strains are two important reasons of decreasing fatigue life . Malekjani investigated the fatigue behaviour of pure aluminium samples subjected to grain refinement by cryorolling.…”

Section: Resultssupporting

confidence: 90%

“…14,15,20 Moreover, creation of bigger shear bands due to a combination of the micro shear bands, which were created owing to intertwined dislocations, and local aggregation of strains are two important reasons of decreasing fatigue life. 35,36 Malekjani 35 investigated the fatigue behaviour of pure aluminium samples subjected to grain refinement by cryorolling. The shear banding and grain coarsening affect the fatigue behaviour of samples.…”

Section: Microstructure Observationsmentioning

confidence: 99%

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Investigation of mechanical properties and fatigue life of ECARed AA5083 aluminium alloy

Sedighi

Monshi

Joudaki

2016

Fatigue Fract Eng Mat Struct

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Equal‐channel angular rolling (ECAR) is a continuous severe plastic deformation process. In this process, severe shear strains apply to the sheet. This strain increases the yield or ultimate strength of sheet without significant change in sheet dimension. In this paper, the effect of ECAR process on mechanical properties and fatigue life of manufactured sheets will be studied. Four AA5083 samples have been prepared and annealed for obtaining stress‐free samples. Three samples have been rolled by the ECAR process with one, two and three passes of rolling, respectively. Mechanical tests including tensile test, hardness and axial fatigue tests have been carried out on prepared samples. Fatigue tests have been implemented according to a strain‐based approach with a constant strain ratio equal to 0.75 and 0.5 Hz frequency of loading. All of the tests have been carried out in controlled laboratory conditions. Results show that the ultimate tensile strength of samples increases with increasing the pass of rolling. Also, the maximum elongation of samples decreases. Maximum elongation was 17% in annealed samples, while it decreases to 10% in samples with three passes of rolling. The hardness of samples has been measured, and the results show an increase in hardness for a higher pass of the ECAR process. Fatigue test results show that fatigue life of AA5083 samples decreases in manufactured sheets of the ECAR process. Also, cyclic softening has been observed in the ECARed sample. The fracture surfaces of samples after fatigue test have been observed with a scanning electron microscope. A comparison of fracture surfaces confirms that the crack growth was intergranular in annealed samples while it changes in ECARed samples to transgranular.

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Section: Resultssupporting

confidence: 90%

Section: Microstructure Observationsmentioning

confidence: 99%

Investigation of mechanical properties and fatigue life of ECARed AA5083 aluminium alloy

Sedighi

Monshi

Joudaki

2016

Fatigue Fract Eng Mat Struct

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“…A typical characteristic of adiabatic shear bands is that the deformation within it is substantially larger than that within the matrix. This localised deformation caused by shear localisation at high strain rates has been observed in many metals, such as steels, 1-4 light metals [5][6][7][8] and Ti alloys. [9][10][11][12][13] These extreme heterogeneous deformations at high strain rates result in high temperatures within the shear band, which cause thermal plastic instabilities in the materials.…”

Section: Introductionmentioning

confidence: 83%

Formation and evolution of shear bands in Zr₄₀Ti₆₀ alloy impacted by Hopkinson bar

Wang

Tan

et al. 2014

Materials Science and Technology

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Shear band formation and evolution in Zr 40 Ti 60 alloy impacted by split Hopkinson pressure bar at different strain rates were investigated. The critical compression strain for the initiation of the shear band was about 15%, and almost no changes were observed with increasing strain rate. The microstructure of the shear band with a width of 13 mm was characterised with elongated and broken grains. Moreover, nanosized dynamic recrystallisation grains (50-100 nm) were observed at the centre of the shear band with widths of 41 and 68 mm. In addition, the microhardness at the centre of the shear band decreased from 560 to 410 HV when the shear band width increased from 13 to 68 mm.

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“…It was shown that grain coarsening within the macroscopic shear bands increases the capacity of these shear bands to accommodate strain by eliminating the heavily worked regions from the shear band, allowing additional strain to be accommodated in those regions. These large strain-free grains are softer than their ultrafine-grained surroundings, and this encourages further localization of deformation within the shear bands [116]. However, such effect may not be expected in other nanostructured materials.…”

Section: Strategies To Increase Fatigue Properties Of Nanostructured mentioning

confidence: 99%

Multifunctional Properties of Bulk Nanostructured Metallic Materials

Sabirov

Enikeev

Murashkin

et al. 2015

Bulk Nanostructured Materials With Multifunctional Properties

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This chapter focuses on multifunctional properties of bulk nanostructured metallic materials and structure-properties relationship therein. The most important structural factors affecting mechanical, physical, and chemical properties of the nanomaterials are discussed, and the strategies to their further improvement are outlined. Special attention is paid to nanostructural design for simultaneous improvement of mutually exclusive properties. Superstrength and Enhanced Mechanical PropertiesAlthough the mechanical and functional properties of all polycrystalline metallic materials are determined by several factors, the grain size of the material generally plays the most significant and often a dominant role. Thus, the strength of different polycrystalline materials is related to the grain size, d, through the Hall-Petch equation which states that the yield stress, σ y , is given bywhere σ o is termed the friction stress and k y the Hall-Petch constant [1,2]. It follows from Eq. 3.1 that the strength increases with a reduction in the grain size and this has led to an ever-increasing interest in fabricating materials with extremely small grain sizes. The fabrication of bulk samples and billets using equal channel angular pressing (ECAP), high pressure torsion (HPT), and other severe plastic deformation (SPD) techniques was a crucial first step in initiating investigations into the properties of bulk nanomaterials because the use of SPD processing permitted, and subsequently fully supported, a series of systematic studies using various nanostructured metallic materials including commercial alloys [3][4][5][6][7][8]

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Shear bands evolution in ultrafine-grained aluminium under cyclic loading

Cited by 20 publications

References 12 publications

Investigation of mechanical properties and fatigue life of ECARed AA5083 aluminium alloy

Investigation of mechanical properties and fatigue life of ECARed AA5083 aluminium alloy

Formation and evolution of shear bands in Zr₄₀Ti₆₀ alloy impacted by Hopkinson bar

Multifunctional Properties of Bulk Nanostructured Metallic Materials

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Shear bands evolution in ultrafine-grained aluminium under cyclic loading

Cited by 20 publications

References 12 publications

Investigation of mechanical properties and fatigue life of ECARed AA5083 aluminium alloy

Investigation of mechanical properties and fatigue life of ECARed AA5083 aluminium alloy

Formation and evolution of shear bands in Zr40Ti60 alloy impacted by Hopkinson bar

Multifunctional Properties of Bulk Nanostructured Metallic Materials

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Product

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Formation and evolution of shear bands in Zr₄₀Ti₆₀ alloy impacted by Hopkinson bar