On the formation and nature of quasi-cleavage fracture surfaces in hydrogen embrittled steels

Martin, May L.; Fenske, Jamey A.; Liu, Grace S.; Sofronis, Petros; Robertson, I. M.

doi:10.1016/j.actamat.2010.11.024

Cited by 320 publications

(109 citation statements)

References 22 publications

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“…In the local area, such as crack tip, microvoids, grain boundaries, matrix/particles interfaces and inclusions, the hydrogen concentration is very high. As the hydrogen migrates via diffusion paths, it encounters hydrogen traps where it is arrested, which leads to the increase in hydrogen concentration of the local area [55,56]. If it exceeds a critical value under certain stress conditions, the crack may initiate there.…”

Section: Fracture Behaviourmentioning

confidence: 99%

Hydrogen pre-charging effects on the notch tensile properties and fracture behaviour of heat-affected zones of thermally aged welds between T24 and T92 creep-resistant steels

Falat¹,

Čiripová²,

Homolová³

et al. 2016

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The effects of thermal exposure at 600• C and subsequent electrolytic hydrogen charging at ambient temperature were studied in terms of their influence on notch-tensile properties and fracture behaviour of individual heat-affected zones (HAZ) of Ni-based transition weldments between T24 and T92 creep-resistant steels. The experimental welded joints were prepared by gas tungsten arc welding using "Inconel-type" filler metal Nirod 600. Post-weld heat treatment (PWHT) was carried out at 720• C for 2 h, followed by passive cooling within tempering furnace. Subsequent long-term ageing of two series of prepared T24/T92 dissimilar welds at 600• C for 1000 and 5000 h, respectively, led to gradual changes in both T24 and T92 HAZ microstructures, which were mainly related to their additional tempering accompanied by the coarsening of original precipitates as well as newly-formed secondary phases. The observed thermally-induced microstructural changes together with subsequently applied hydrogen charging effects resulted in complex variations in tensile properties and fracture behaviour of individual HAZ regions related to the pre-existing differences in their initial tempering grade due to the used PWHT procedure. K e y w o r d s : creep-resistant steels, dissimilar welding, isothermal ageing, hydrogen embrittlement, mechanical properties, fracture mechanisms

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Section: Fracture Behaviourmentioning

confidence: 99%

Hydrogen pre-charging effects on the notch tensile properties and fracture behaviour of heat-affected zones of thermally aged welds between T24 and T92 creep-resistant steels

Falat¹,

Čiripová²,

Homolová³

et al. 2016

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show abstract

“…Many theories have been proposed to explain this phenomenon including hydrogen-enhanced localized plasticity mechanism, [1][2][3][4] hydrogen-enhanced decohesion mechanism [5][6][7] and hydrogen-enhanced vacancies and nanovoids coalescence mechanism. [8][9][10][11] Among these explanations, there is consensus in that mobile hydrogen causes degradation in steels.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Traps and Hydrogen Induced Cracking in 20CrMo Steel

Zhu

Yao

et al. 2017

ISIJ Int.

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The hydrogen trapping sites of commercial 20CrMo steel samples with electrochemically charged hydrogen were characterized by thermoelectric power (TEP) and scanning Kelvin probe force microscope (SKPFM). A surface potential drop of about 190 mV was found for the globular MnS inclusion and 150 mV for the elongated one due to the hydrogen absorption of MnS inclusions. Similar to thermal desorption measurement, TEP is a potential method in analyzing hydrogen traps of solid solution, dislocations and irreversible traps. The fracture morphology and hydrogen induced cracking can be explained by combined hydrogen embrittlement mechanisms. Although hydrogen induced cracks are found to initiate at the elongated inclusions, only longitudinal cracks were observed in this study which is not detrimental to the embrittlement.

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“…[15] Furthermore, high-density slip bands are observed just beneath the fracture surface cut with a focused ion beam, using transmission electron microscopy. [36,37] These studies indicate that quasi-cleavage is not a brittle but a ductile fracture locally. That is, movement of dislocations plays an important role in quasi-cleavage fracture.…”

Section: Methods Of Evaluating Susceptibility To Delayed Fracture Bmentioning

confidence: 98%

Method of Evaluating Delayed Fracture Susceptibility of Tempered Martensitic Steel Showing Quasi-Cleavage Fracture

Matsumoto

Takai

2016

Metall Mater Trans A

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The difference in the hydrogen charging methods, immersion in a NH 4 SCN aqueous solution, and cathodic electrolysis in a NaOH aqueous solution, did not affect the hydrogen state present in the steel, but it did affect the surface state of the specimens through corrosion, causing fracture strength to fluctuate in tensile testes. As for stress application method, the fracture strength at lower crosshead speeds in tensile tests was consistent with that found for hydrogen precharging prior to stress application in CLTs as long as hydrogen charging was conducted by cathodic electrolysis. However, the fracture strength obtained with concurrent hydrogen charging without precharging prior to stress application in CLTs was higher than that with hydrogen precharging prior to stress application in CLTs regardless of the same hydrogen content. In other words, delayed fracture susceptibility was affected by the order of hydrogen charging and stress application for quasi-cleavage fracture associated with local plastic deformation, i.e., dislocation motion. Therefore, by taking into account the cathodic electrolysis in the NaOH solution, the low crosshead speed and the order of hydrogen charging and stress application, the fracture strength in CLTs, and tensile tests coincided with respect to quasi-cleavage fracture even though the stress application methods were different.

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On the formation and nature of quasi-cleavage fracture surfaces in hydrogen embrittled steels

Cited by 320 publications

References 22 publications

Hydrogen pre-charging effects on the notch tensile properties and fracture behaviour of heat-affected zones of thermally aged welds between T24 and T92 creep-resistant steels

Hydrogen pre-charging effects on the notch tensile properties and fracture behaviour of heat-affected zones of thermally aged welds between T24 and T92 creep-resistant steels

Hydrogen Traps and Hydrogen Induced Cracking in 20CrMo Steel

Method of Evaluating Delayed Fracture Susceptibility of Tempered Martensitic Steel Showing Quasi-Cleavage Fracture

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