Gleeble Testing to Assess Solid/Liquid Metal Embrittlement of Gun Steels by Copper

Vigilante, Gregory N.; Izzo, John R.; Witherell, M. D.; Smith, Stephen B.

doi:10.1080/10426914.2011.648693

Cited by 16 publications

(4 citation statements)

References 4 publications

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“…Furthermore, it was also found that the copper or brass was deposited on the grooves' surface after tests owing to severe friction between the groove and the rotating band. In fact, coppering always happens within the gun bore surface under actual firing conditions, and it should be eliminated to avoid any adverse effect on accuracy [17]. Figure 13 shows an engraved rotating band of a recovered projectile after actual firing.…”

Section: Dynamic Impact Engraving Of Rotating Bandsmentioning

confidence: 99%

Tribology of rotating band and gun barrel during engraving process under quasi-static and dynamic loading

Wu¹,

Zheng²,

Tian³

et al. 2014

Friction

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Abstract:The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics, which has not been thoroughly understood thus far. An understanding of this process is of great importance from the viewpoints of optimal design, manufacturing, use, and maintenance of gun and projectile. In this paper, the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi-static and dynamic loading conditions. The quasi-static engraving tests were performed on a CSS-88500 electronic universal testing machine (EUTM) and a special gas-gun-based test rig was designed for dynamic impact engraving of the rotating bands. The mechanical behaviors of copper and nylon were investigated under strain rates of 10 −3 s −1 and 2 × 10 3 s −1 using an MTS 810 and a split Hopkinson pressure bar (SHPB), respectively. Morphologies of the worn surfaces and cross-sectional microstructures were observed with scanning electron microscope (SEM) and optical microscope (OM). It was found that large deformation and severe friction occur during engraving. The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface. The structure of the rotating band and gun bore, band material, and loading rate have great effects on band engraving. The flow stress-strain of the copper strongly depends on the applied strain rate. It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.

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Section: Dynamic Impact Engraving Of Rotating Bandsmentioning

confidence: 99%

Tribology of rotating band and gun barrel during engraving process under quasi-static and dynamic loading

Wu¹,

Zheng²,

Tian³

et al. 2014

Friction

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“…First, pos-sessing a high concentration of free electrons, copper is generally not accepted as surfactant. At the same time, it causes LME, as well as SME, in the artillery gun tubes be present on the projectile to provide a gas seal and to assist its spin up for providing subsequent flight stabilization (see, e.g., [10]). However, copper is successfully used as alloying element in austenitic steels for production of corrosion-resistant wire and ropes where its occurrence substantially eases drawing of steel wire and increases plasticity (e.g., [69]).…”

Section: Hypotheses For Surfactants-caused Embrittlementmentioning

confidence: 99%

“…A number of original research papers, review articles and monographies are concerned with this not ordinary phenomenon, e.g., [5][6][7][8][9][10]. Nevertheless, an operating mechanism remains so far debatable.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Embrittlement of Metals by Surface-Active Elements

Teus¹,

Shanina²,

Konchits³

et al. 2018

Metallofiz. Noveishie Tekhnol.

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The nature of mechanical degradation of metals caused by surface-active elements is studied based on the effects of iodine and gallium in austenitic steels and using ab initio calculations and experimental measurements of electronic structure, X-ray diffraction, mechanical spectroscopy, and mechanical tests. A significant increase in the density of electron states at the Fermi level for iodine in f.c.c. iron is shown that is in consistent with the measurements of the increased concentration of free electrons caused by iodine in austenitic steels. Consequently, the increase in mobility of dislocations by iodine and gallium in austenitic steels is revealed. The localization of the enhanced plastic deformation is discussed as a condition for brittleness. The obtained results are at variance with the widely spread opinion about the determining role of surface energy in a liquid-metal brittleness and, instead, are interpreted based on the correlation between atomic interactions and dislocation properties. Applicability of the available HELP and AIDE hypotheses is discussed.Key words: f.c.c. iron, austenitic steel, surfactants, electronic structure, dislocations, mechanical properties.Природу механічної деґрадації металів, яку спричинено дією поверхнево- Ключові слова: ÃЦÊ-çаліçо, аустенітна сталü, сурôактанти, електронна структура, дислокації, механічні властивості.Природа механическоé деградации металлов, обусловленноé поверхност-но-активнûми элементами, бûла иçучена, основûваясü на влиянии éода и галлия на аустенитнûе стали и исполüçуя ab initio-расчётû и эксперимен-талüнûе исследования электронноé структурû, рентгеновскую диôрак-цию, механическую спектроскопию и механические испûтания. Покаçа-но существенное повûøение плотности электроннûх состояниé на уровне Ôерми в случае éода в ÃЦÊ-желеçе, что согласуется с иçмерениями, в ко-торûх бûла çаôиксирована повûøенная концентрация свободнûх элек-тронов, вûçванная éодом в аустенитнûх сталях. Êак следствие, установ-лено повûøение мобилüности дислокациé, вûçванное éодом и галлием в аустенитнûх сталях. Îбсуждается ролü локалиçации повûøенноé пла-стическоé деôормации в качестве условия хрупкости. Полученнûе ре-çулüтатû противоречат øироко распространённому мнению об определя-ющеé роли поверхностноé энергии в жидкометаллическоé хрупкости и, вместо этого, интерпретируются, основûваясü на корреляции между атомнûми вçаимодеéствиями и дислокационнûми своéствами. Îбсужда-ется применимостü гипотеç HELP и AIDE.Ключевые слова: ÃЦÊ-желеçо, аустенитная сталü, сурôактантû, элек-тронная структура, дислокации, механические своéства.

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“…A number of original research papers, review articles and monographies are concerned with this not ordinary phenomenon [4][5][6][7][8][9]. Nevertheless, an operating mechanism remains to be debatable.…”

Section: Introductionmentioning

confidence: 99%

On the Nature of Similarity in Embrittlement of Metals by Hydrogen and Surfactants

et al. 2017

MSEIJ

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A mechanism for a similar effect of hydrogen and surface-active elements, surfactants, on the structure and properties of metals is discussed based on studies of austenitic steels and using the ab initio calculations and experimental measurements of the electron structure, mechanical spectroscopy and tension tests. The similarity is originated from the local enhancement of the metallic character of interatomic bonds. The obtained results are interpreted within the frame of the electron approach to the hydrogen-enhanced localized plasticity phenomenon, HELP, in hydrogen embrittlement. The surfactants increase the density of electron states at the Fermi level and, correspondingly, the concentration of free electrons. As a response, a local decrease of the shear modulus resulted in the initiation of dislocation sources, decrease of the line tension of dislocations and distance between their assembles is expected, which facilitates the opening and propagation of cracks and mechanical degradation. The comparison with the adsorption-induced dislocation emission hypothesis, AIDE, for hydrogen and liquid metal embrittlements is carried out. Keywords: On the Nature of Similarity in Embrittlement of Metals by Hydrogen and Surfactants 2/10Copyright: ©2017 Gavriljuk et al.Important for clarification of the operative mechanism was the observation that, including LME, embrittlement by surfactants is accompanied by a local increase of plasticity [22][23][24]. In other words, the locally enhanced plastic deformation precedes the macrobrittle fracture. This unusual behavior was firstly interpreted as a local disintegration of solids resulted in colloidal disperse systems [4,5]. Later, such approach was supported by the ideas about liquid channels [14,15] and corresponding grain boundary phase transitions [25,26].However, such interpretation of preceded plastic deformation is seriously discredited by a remarkable similarity between LME and hydrogen embrittlement, HE, where local plastic flow always precedes the fracture. Systematic comparative studies of LME and HE were carried out by Lynch [27]. Based on these studies, he has proposed the adsorption-induced localized-slip process to be responsible for both the LME and HE phenomena [28] and, correspondingly, developed the hypothesis of adsorption-induced dislocation emission, AIDE [29]. Its main idea amounts to the adsorption of hydrogen and surfactant atoms at the internal crack tips, which facilitates the nucleation and emission of dislocations. Once nucleated, the dislocations can readily move away from the crack tip under applied stress.Along with AIDE hypothesis, hydrogen embrittlement of metals is described by hypotheses of hydrogen-enhanced decohesion, HEDE, hydrogen-enhanced localized plasticity, HELP, and hydrogen-enhanced strain-induced vacancies, HESIV. Their critical analysis is presented, e.g., in the review articles [29,30]. The AIDE and HELP hypotheses seem to be the most acceptable for application to the both HE and LME processes.Probably first time, the ...

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Gleeble Testing to Assess Solid/Liquid Metal Embrittlement of Gun Steels by Copper

Cited by 16 publications

References 4 publications

Tribology of rotating band and gun barrel during engraving process under quasi-static and dynamic loading

Tribology of rotating band and gun barrel during engraving process under quasi-static and dynamic loading

Mechanism of Embrittlement of Metals by Surface-Active Elements

On the Nature of Similarity in Embrittlement of Metals by Hydrogen and Surfactants

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