Direct measurement of isothermal flow stress of metals at elevated temperatures and high strain rates with application to Ta and TaW alloys

Nemat‐Nasser, Sia; Isaacs, Jon

doi:10.1016/s1359-6454(96)00243-1

Cited by 234 publications

(118 citation statements)

References 15 publications

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“…Bai et al [69] Chen and Vecchio [70] Uranium, hafnium Magness [71] Subhash et al [72] Tantalum Chen et al [43] Vecchio et al [74] Nemat Nasser et al [75] Hynes and Vecchio [193] Fig. 1-Experimental methods used to generate the shear bands: (a) thin-walled-tube specimen for torsion loading, (b) hat-shaped specimen for forced shear localization, and (c) TWC technique using explosive collapse.…”

Section: Ti and Alloysmentioning

confidence: 99%

“…Recrystallization arising from high-strain-rate loading has been well documented by some investigators in steels (Glass and Moss in 1961, [177] Mataya and Carr in 1982, [178] Meyers and Xu, [63] Li et al, [179] Lins et al [180] ), in titanium (Meyers and Pak in 1986, [35] Xu and Meyers in 2003, [138] Chichili et al [38] ), in copper (Andrade et al in 1994, [181] Hines and Vecchio in 1995, [182] Murr et al in 1995, [183] and Hines et al in 1998, [184] ), in tantalum (Pappu et al in 1995, [185] Murr et al in 1994, [186] Nesterenko et al in 1997, [187] Meyers and Chen in 1995, [43,73] and Nemat Nasser et al [75] ), in aluminum-lithium alloys (Xu et al [77] and Meyers et al in 2000 [187,188] ), in Al/SiC p composites (Xu et al [162] ), and in Ni-Cu alloys (Li et al in 2000 [189] ). It is generally accepted that the deformation and associated temperature rise during high-strain-rate loading are, therefore, sufficient to produce new recrystallized grains in the shear bands, although it is not clear at present that this recrystallized microstructure develops simultaneously with deformation (dynamic recrystallization (DRX)) or subsequent to deformation (static recrystallization).…”

Section: G Recrystallizationmentioning

confidence: 99%

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Shear Localization in Dynamic Deformation: Microstructural Evolution

Jing-hua

Bai

et al. 2008

Metall Mater Trans A

251

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Investigations made by the authors and collaborators into the microstructural aspects of adiabatic shear localization are critically reviewed. The materials analyzed are low-carbon steels, 304 stainless steel, monocrystalline Fe-Ni-Cr, Ti and its alloys, Al-Li alloys, Zircaloy, copper, and Al/SiC p composites. The principal findings are the following: (a) there is a strain-ratedependent critical strain for the development of shear bands; (b) deformed bands and whiteetching bands correspond to different stages of deformation; (c) different slip activities occur in different stages of band development; (d) grain refinement and amorphization occur in shear bands; (e) loss of stress-carrying capability is more closely associated with microdefects rather than with localization of strain; (f) both crystalline rotation and slip play important roles; and (g) band development and band structures are material dependent. Additionally, avenues for new research directions are suggested.

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Section: Ti and Alloysmentioning

confidence: 99%

Section: G Recrystallizationmentioning

confidence: 99%

Shear Localization in Dynamic Deformation: Microstructural Evolution

Jing-hua

Bai

et al. 2008

Metall Mater Trans A

251

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“…The SHPB has been widely used to investigate the dynamic mechanical properties of materials under uniaxial compression [5,6,[8][9][10][11]. The SHPB apparatus comprises three elastic bars that are the striker, the incident bar, and the transmitted bar.…”

Section: Introductionmentioning

confidence: 99%

Effects of imperfect experimental conditions on stress waves in SHPB experiments

Yin

Yan

et al. 2015

Acta Mech. Sin.

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Experimental and numerical simulations were undertaken to estimate the effects of imperfect conditions on stress waves in split Hopkinson pressure bar (SHPB) experiments. The photonic Doppler velocimetry (PDV) measurement results show that the rise and fall times of an incident wave increases with an increasing inclination angle; also, the fluctuations of the incident wave disappear gradually with the increase of inclination angle. The following characteristics for various defects in the SHPB were obtained by numerical simulation: (1) the influence of a curved bar was negligible; (2) misalignment modestly affects the fluctuation characteristics, and bending waves were generated at this condition; (3) inclination and indentation of the impact endsurface had a great impact on the incident waves, and both of them increase the rise time of the incident wave by increasing the degree of defects. In view of the results, misalignment, inclination, and indentation in SHPB experiments should be minimized.

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“…The deformation of tantalum at rates observed here has been shown to be well represented by several constitutive models 9,[25][26][27][28] which are based upon the thermal activation kinetics developed by Kocks et al 29 We employ here the isotropic mechanical threshold stress (MTS) model, which has been well established for tantalum and is due to the work of Follansbee and Kocks, 30 Chen and Gray, 9 and Maudlin et al 22 The MTS model is based on the concept of a superposition of resistances to the glide of dislocations. Generally, they are grouped as athermal barriers (e.g., grain boundaries) and thermally influenced barriers (e.g., Peierls stress-intrinsic lattice resistance, forest dislocations, dislocation structure, and solute atoms).…”

Section: -5mentioning

confidence: 62%

Response and representation of ductile damage under varying shock loading conditions in tantalum

Bronkhorst

Gray

Addessio

et al. 2016

Journal of Applied Physics

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The response of polycrystalline metals, which possess adequate mechanisms for plastic deformation under extreme loading conditions, is often accompanied by the formation of pores within the structure of the material. This large deformation process is broadly identified as progressive with nucleation, growth, coalescence, and failure the physical path taken over very short periods of time. These are well known to be complex processes strongly influenced by microstructure, loading path, and the loading profile, which remains a significant challenge to represent and predict numerically. In the current study, the influence of loading path on the damage evolution in high-purity tantalum is presented. Tantalum samples were shock loaded to three different peak shock stresses using both symmetric impact, and two different composite flyer plate configurations such that upon unloading the three samples displayed nearly identical "pull-back" signals as measured via rear-surface velocimetry. While the "pull-back" signals observed were found to be similar in magnitude, the sample loaded to the highest peak stress nucleated a connected field of ductile fracture which resulted in complete separation, while the two lower peak stresses resulted in incipient damage. The damage evolution in the "soft" recovered tantalum samples was quantified using optical metallography, electron-back-scatter diffraction, and tomography. These experiments are examined numerically through the use of a model for shock-induced porosity evolution during damage. The model is shown to describe the response of the tantalum reasonably well under strongly loaded conditions but less well in the nucleation dominated regime. Numerical results are also presented as a function of computational mesh density and discussed in the context of improved representation of the influence of material structure upon macro-scale models of ductile damage. V C 2016 AIP Publishing LLC.

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Direct measurement of isothermal flow stress of metals at elevated temperatures and high strain rates with application to Ta and TaW alloys

Cited by 234 publications

References 15 publications

Shear Localization in Dynamic Deformation: Microstructural Evolution

Shear Localization in Dynamic Deformation: Microstructural Evolution

Effects of imperfect experimental conditions on stress waves in SHPB experiments

Response and representation of ductile damage under varying shock loading conditions in tantalum

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