Effect of hydrogen on stability of micro cracks in iron and steel

Garofalo, F.; Chou, Y. T.; Ambegaokar, Vinay

doi:10.1016/0001-6160(60)90103-6

Cited by 66 publications

(19 citation statements)

References 12 publications

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“…HE depends on many factors such as the composition, temperature, residual stress, microstructure, and surface condition of steels. To explain the effect of hydrogen on the mechanical properties of steel, mechanisms such as internal pressure [8][9][10][11], surface energy [12], decohesion [13], hydrogen-enhanced plasticity [14], and hydrogen-enhanced strain-induced vacancies [15][16][17] have been proposed. However, HE has not yet been fully clarified due to the following uncertainties: firstly, why SIM increases the ductility of austenitic stainless steel, and secondly, why hydrogen suppresses the SIM formation in H-charged austenitic stainless steel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

Bak

Abro

Lee

2016

Metals

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Plastic deformation and strain-induced martensite (SIM, α 1 ) transformation in metastable austenitic AISI 304 stainless steel were investigated through room temperature tensile tests at strain rates ranging from 2ˆ10´6 to 2ˆ10´2/s. The amount of SIM was measured on the fractured tensile specimens using a feritscope and magnetic force microscope. Elongation to fracture, tensile strength, hardness, and the amount of SIM increased with decreasing the strain rate. The strain-rate dependence of RT tensile properties was observed to be related to the amount of SIM. Specifically, SIM formed during tensile tests was beneficial in increasing the elongation to fracture, hardness, and tensile strength. Hydrogen suppressed the SIM formation, leading to hydrogen softening and localized brittle fracture.

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Section: Introductionmentioning

confidence: 99%

Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

Bak

Abro

Lee

2016

Metals

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“…In the sixties, they have given a critical argument against the pressure-expansion hypothesis for hydrogen embrittlement of which the essence was the precipitation of gaseous hydrogen in pre-existing microvoids and their growth under increased internal hydrogen pressure (see, e.g. [30,31]. However, as was shown in [32], despite on the absence of cracks, the gaseous hydrogen of 1 bar pressure caused a greater embrittlement of high strength steels in comparison with electrolytic charging.…”

Section: Discussionmentioning

confidence: 99%

Hydrogen Grain Boundary Segregation and Migration in the Alpha-Iron

Gavriljuk¹,

Teus²

2017

Metallofiz. Noveishie Tekhnol.

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Based on the difference in diffusion mechanisms of substitutional and interstitial atoms and using molecular dynamics simulation of hydrogen migration, it is shown that accelerated hydrogen flux in the polycrystalline iron observed during cathodic charging cannot originate from the enhanced hydrogen grain-boundary diffusion. A possible role of grain-boundary cracking is supposed.Key words: hydrogen diffusion, grain boundaries, molecular dynamics simulation.Ґрунтуючись на відмінностях механізмів дифузії атомів заміщення та втілення і використовуючи молекулярно-динамічні розрахунки міґрації атомів Гідроґену, показано, що прискорений потік водню в полікристалі-чному залізі, який спостерігається в процесі катодного наводнення, не може бути наслідком прискореної зерномежової дифузії водню. Розгляда-ється можлива роль зерномежового розтріскування.Ключові слова: дифузія водню, межі зерен, молекулярна динаміка.Основываясь на отличиях механизмов диффузии атомов замещения и внедрения и используя моделирование методом молекулярной динамики миграции водорода, показано, что ускоренный поток водорода в поликри-сталлическом железе, который наблюдается в процессе катодного наводо-раживания, не может быть следствием ускоренной зернограничной диф-фузии водорода. Рассмотрена возможная роль зернограничного растрес-кивания.

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“…However, it is not the case for gaseous hydrogenation. It is worth noting in this relation that one of the earliest proposed mechanisms of HE was concerned with the so-called pressure-expansion theory [59], which included precipitation of gaseous hydrogen in the microvoids, their growth under increased internal hydrogen pressure and consequent plastic deformation leading to microcracks or void coalescence. Critical for estimation of that mechanism were the experimental data [60], according to which the gaseous hydrogenation at 1 bar pressure without crack formation was found to cause a greater embrittlement of high strength steels in comparison with electrolytic charging accompanied by crack nucleation.…”

Section: Comparative Analysis Of Aide and Help Hypothesesmentioning

confidence: 99%

Untitled

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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Effect of hydrogen on stability of micro cracks in iron and steel

Cited by 66 publications

References 12 publications

Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

Hydrogen Grain Boundary Segregation and Migration in the Alpha-Iron

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