Hydrogen absorption of incoherent TiC particles in iron from environment at high temperatures

Wei, Fu-Gao; Tsuzaki, Kaneaki

doi:10.1007/s11661-004-0060-5

Cited by 55 publications

(34 citation statements)

References 16 publications

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“…Both morphology and size of transition-metal carbides precipitated in steels can vary significantly depending on composition and manufacturing conditions (e.g., thermal treatment) [20][21][22][39][40][41] . Furthermore, the carbides are often sub-stoichiometric, containing a large amount of C vacancies.…”

Section: Theoretical Approachmentioning

confidence: 99%

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First-principles investigation of hydrogen interaction with TiC precipitates inα-Fe

et al. 2016

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A correct description of hydrogen diffusion and trapping is the prerequisite for an understanding of the phenomenon of hydrogen embrittlement. In this study, we carried out extensive first-principles calculations based on density functional theory to investigate the interaction of H with TiC precipitates that are assumed to be efficient trapping agents mitigating HE in advanced high-strength steels. We found that there exists a large variety of possible trapping sites for H associated with different types of interfaces between the TiC particle and the Fe matrix, with misfit dislocations and other defects at these interfaces, and with carbon vacancies in TiC. The most efficient trapping by more than 1 eV occurs at carbon vacancies in the interior of TiC particles. However, these traps are difficult to populate at ambient temperatures since the energy barrier for H entering the particles is high. H trapping at the semicoherent interfaces between the TiC particles and the Fe matrix is moderate, ranging from 0.3 to 0.5 eV. However, a sufficiently large concentration of the carbide particles can significantly reduce the amount of H segregated at dislocation cores in the Fe matrix. A systematic comparison of the obtained theoretical results with available experimental observations reveals a consistent picture of hydrogen trapping at the TiC particles that is expected to be qualitatively valid also for other carbide precipitates with the rock-salt crystal structure.

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Section: Theoretical Approachmentioning

confidence: 99%

“…According to experimental studies [20][21][22] , the TiC particles in the Fe matrix can form also interfaces with other ORs, in particular those with (110) Fe /(001) TiC orientation. In this case, it is more difficult to find a geometrically favorable orientation of the two crystals with a small lattice mismatch.…”

Section: Other Interfacesmentioning

confidence: 99%

First-principles investigation of hydrogen interaction with TiC precipitates inα-Fe

et al. 2016

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“…Grain boundaries and dislocations are weak traps with low binding energies. On the other hand, the interfaces of non-metallic inclusions such as MnS, oxides and oxysulphides of Al and Ca, and precipitates like TiC are considered to be strong irreversible traps for hydrogen at normal service temperatures [2,[8][9][10] [2-4, 6, 11-16]. Large inclusions such as elongated MnS and clusters or stringers of oxides have been reported to increase the susceptibility of steels to HIC [17].…”

Section: Introductionmentioning

confidence: 99%

Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking

Hejazi

Haq

Yazdipour

et al. 2012

Materials Science and Engineering: A

118

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The influence of composition and microstructure on susceptibility to hydrogen induced cracking (HIC) was investigated in high strength pipeline steels, with Mn contents of 1.2% (standard, X70), and 0.5% (medium, MX70). The HIC resistance of the simulated coarse grained heat affected zone microstructures and normalized X70 transfer bar was also investigated. Notched and fatigue pre-cracked samples were charged with hydrogen prior to three point bend tests. The conditional fracture toughness JQ was determined. The results are discussed in relation to grain size, microstructure, composition and the type and distribution of non-metallic inclusions and precipitates. Published as "Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking" AbstractHydrogen, even in very low concentrations, can diffuse to regions of high stress concentration resulting in a degradation of mechanical properties. However, the transport of hydrogen depends on the interaction between hydrogen atoms and microstructural traps which, in turn, is related to microstructure. The influence of composition and microstructure on susceptibility to hydrogen embrittlement was investigated by selecting pipeline steels with different Mn contents, i.e., standard Mn (X70) and medium Mn (MX70) strips. The HAZ (heat affected zone) microstructures of these strips as well as a normlised transfer bar (TB) were also investigated. HAZ simulations were conducted using Gleeble thermo-mechanical machine to simulate a thermal cycle typical of inservice repairs. Notched and fatigue pre-cracked samples were subjected to electrochemical hydrogen charging using a solution of H 2 SO 4 and NaAsO 2 to achieve 2 and 4 ppm hydrogen content. Three point bend tests were conducted on as-received and hydrogen-charged samples. The X70 strip exhibited a higher J Q than the MX70 strip before and after charging, whereas the TB displayed the lowest J Q . The fracture performance of both steels deteriorated almost linearly with an increase in the hydrogen content. Because of their coarser prior austenite grain sizes and the presence of relatively hard bainitic-ferrite structure with martensite/austenite islands, the simulated HAZ microstructures of the two steels demonstrated significantly lower fracture resistance both with and without hydrogen. The results obtained were compared and discussed in relation to the grain size, microstructure, composition and the type and distribution of precipitates in the samples.

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“…Wurushihara et al conducted SSRT of round smooth bar specimen of high strength steels containing hydrogen traps related to the additive V 29,53) and/or Ti [54][55][56] after CCT or immersion in an acidic aqueous solution, and evaluated the reduction of elongation.…”

Section: Introductionmentioning

confidence: 99%

“…To avoid hydrogen release from the steels which do not contain hydrogen traps such as carbides of V 29,53) and Ti, [54][55][56] the environment surrounding the specimen was kept wet during those tensile tests.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Delayed Fracture Property of High Strength Bolt Steels

Akiyama

2012

ISIJ Int.

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Experimental studies attempting to evaluate the delayed fracture property of high strength bolt steels by using slow strain rate tests (SSRT) of circumferentially notched round bar specimens are reviewed in this paper. The relationship between the notch tensile strength (NTS) of the hydrogen-precharged specimens and the hydrogen content was approximated by power law relationship. It has been found that the local stress and the local diffusible hydrogen concentration control the occurrence of delayed fracture. To take into account the effect of hydrogen uptake from the environment, the notched bar specimens were subjected to cyclic corrosion test (CCT) and outdoor exposure, and their NTSs were measured using SSRT. The susceptibility of high strength steels to delayed fracture estimated from the decrease of NTS was correspondent to the fracture ratio of high strength bolts of the steels obtained by outdoor exposure tests, and was successfully evaluated with consideration of hydrogen uptake. Hydrogen entry behavior under CCT was monitored by electrochemical hydrogen permeation test, and continuous increase in hydrogen entry with growth of rust layer was observed. It is suggested that the "delay" of delayed fracture is the time required for the enhancement of the hydrogen entry efficiency.KEY WORDS: delayed fracture; hydrogen embrittlement; high strength steel; slow strain rate test; atmospheric corrosion; electrochemical hydrogen permeation; cyclic corrosion test; exposure test.

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Hydrogen absorption of incoherent TiC particles in iron from environment at high temperatures

Cited by 55 publications

References 16 publications

First-principles investigation of hydrogen interaction with TiC precipitates inα-Fe

First-principles investigation of hydrogen interaction with TiC precipitates inα-Fe

Effect of manganese content and microstructure on the susceptibility of X70 pipeline steel to hydrogen cracking

Evaluation of Delayed Fracture Property of High Strength Bolt Steels

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