Atomic-scale investigation of deep hydrogen trapping in NbC/α-Fe semi-coherent interfaces

Shi, Rongjian; Ma, Yuan; Wang, Zidong; Gao, Lei; Yang, Xu Sheng; Li, Qiao; Pang, Xiaolu

doi:10.1016/j.actamat.2020.09.031

Cited by 142 publications

(39 citation statements)

References 70 publications

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“…Recently, researchers have gradually turned their attention to whether inclusions would affect proeutectoid ferrite. [20][21][22] However, the influence of inclusions on the formation of proeutectoid ferrite is mainly concentrated in the heat-affected zone of the weld, [23,24] and there are few studies on the cast slab or billet. [25] The types of inclusions in heat-affected zone of the weld are complex and the number of inclusions is huge.…”

Section: Introductionmentioning

confidence: 99%

The Formation Mechanism of Proeutectoid Ferrite on Medium-Carbon Sulfur-Containing Bloom

Lü

Fan

Wang

et al. 2021

Metall Mater Trans B

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Proeutectoid ferrite is harmful to the toughness of slab or billet during continuous casting since it can provide crack propagation path at low temperature preferentially. Single variable controlling method is used in this paper and the results show that the proeutectoid ferrite of medium-carbon sulfur-containing bloom is more developed than that of sulfur-free bloom, especially on the surface. Thermodynamic calculations show that the formation area of ferrite increased with the increase of sulfur content, suggesting that sulfur is beneficial to the formation of ferrite. MnS inclusions are the core of proeutectoid ferrite and the number of precipitated MnS inclusion is positively correlated to the area fraction of precipitated proeutectoid ferrite. FIB-TEM technique is further conducted to investigate the orientation relationship and crystal structure of MnS inclusion and proeutectoid ferrite. The results show that MnS inclusion are not directly related to the formation of proeutectoid ferrite. Mn-depleted zone around MnS inclusion observed in EDS and EPMA results is the direct inducing factor for the formation of proeutectoid ferrite in medium-carbon sulfur-containing bloom.

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Section: Introductionmentioning

confidence: 99%

The Formation Mechanism of Proeutectoid Ferrite on Medium-Carbon Sulfur-Containing Bloom

Lü

Fan

Wang

et al. 2021

Metall Mater Trans B

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“…Moreover, there was a similar size distribution of Cr-rich carbides in two steels, but more nanosized NbC carbides precipitated during tempering are shown in Figure 6. M. Ohnuma et al [45] confirmed hydrogen trapped by nanosized NbC in steel using smallangle neutron scattering, and the irreversible hydrogen tapping in nanosized NbC/BCC iron semi-coherent interfaces was proved in the work of Shi et al [46]. Consequently, the dispersed nanosized NbC carbides formed during tempering contributed a beneficial effect on SSCC resistance.…”

Section: Discussionmentioning

confidence: 94%

Effects of the Primary NbC Elimination on the SSCC Resistance of a HSLA Steel for Oil Country Tubular Goods

et al. 2021

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Sulfide stress corrosion cracking (SSCC) has been of particular concern in high strength low alloyed (HSLA) steels used in the oil industry, and the non-metallic inclusions are usually considered as a detrimental factor to the SSCC resistance. In the present work, continuous casting (CC) and electroslag remelting (ESR) were adopted to fabricate a 125 ksi grade steel in order to evaluate the effect of microstructure with and without primary NbC carbides (inclusions) on the SSCC resistance in the steel. It was found that ESR could remove the primary NbC carbides, and hence, slightly increase the strength without deteriorating the SSCC resistance. The elimination of primary NbC carbides caused two opposite effects on the SSCC resistance in the studied steel. On the one hand, the elimination of primary NbC carbides increased the dislocation density and the proportion of high angle boundaries (HABs), which was not good to the SSCC resistance. On the other hand, the elimination of primary NbC carbides also induced more uniform nanosized secondary NbC carbides formed during tempering, providing many irreversible hydrogen traps. These two opposite effects on SSCC resistance due to the elimination of primary NbC carbides were assumed to be offset, and thus, the SSCC resistance was not greatly improved using ESR.

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“…However, the strain energies of the incoherent interface of semicoherent or incoherent particles were extremely minute, and these interfaces trapped hydrogen mainly by the interfacial energies, which thus led to the different desorption activation energies of the three peaks. In addition, the hydrogen adsorption capability of the coherent interfaces was strengthened by defects such as vacancies and dislocations at the coherent interfaces, [55,56] which also led to different desorption energies. Above all, peaks 1, 2, and 3 might be attributed to the precipitate/ferrite interfaces with nonuniform activation energy of hydrogen desorption.…”

Section: Tds Resultsmentioning

confidence: 99%

Improved Stress Corrosion Cracking Resistance of High‐Strength Low‐Alloy Steel in a Simulated Deep‐Sea Environment via Nb Microalloying

Zhao

Fan

Zhao

et al. 2021

steel research int.

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Microstructure observations, thermal desorption spectroscopy (TDS) tests, hydrogen permeation measurements, electrochemical tests, and slow strain rate tensile (SSRT) tests are conducted investigate the beneficial effect of Nb microalloying on the stress corrosion cracking (SCC) behavior of high-strength low-alloy (HSLA) steels in a simulated deep-sea environment. The results show that the addition of Nb significantly decreases the SCC susceptibility of HSLA steel in a simulated deep-sea environment, and the role of Nb is attributed to microstructure optimization and the strong hydrogen-trap function of nanosized NbC precipitates with hydrogen activation energy up to 100.5 kJ mol À1 . In the simulated deep-sea environment, the SCC resistance of HSLA steel is enhanced by microstructure optimization and the hydrogen-trap function via Nb microalloying, and both anodic dissolution (AD) and hydrogen embrittlement (HE) are weakened. Moreover, the improvement of SCC resistance of HSLA steel with a higher hydrogen concentration via Nb microalloying is more obvious, in which the decrease of hydrogen-induced anodic dissolution (HIAD) and HE effects is more distinct, and the strong hydrogen-trap effect of NbC precipitates is the predominant mechanism to improve SCC resistance.

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Atomic-scale investigation of deep hydrogen trapping in NbC/α-Fe semi-coherent interfaces

Cited by 142 publications

References 70 publications

The Formation Mechanism of Proeutectoid Ferrite on Medium-Carbon Sulfur-Containing Bloom

The Formation Mechanism of Proeutectoid Ferrite on Medium-Carbon Sulfur-Containing Bloom

Effects of the Primary NbC Elimination on the SSCC Resistance of a HSLA Steel for Oil Country Tubular Goods

Improved Stress Corrosion Cracking Resistance of High‐Strength Low‐Alloy Steel in a Simulated Deep‐Sea Environment via Nb Microalloying

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