Development of Quasi-Cleavage Crack Leading to Fracture of Hydrogen Charged High Strength Steel.

Oyanagi, Mitsushi; Suzuki, Tetsuya; Yamada, Kazuo

doi:10.2472/jsms.51.561

Cited by 4 publications

(3 citation statements)

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“…14. QC crack propagation due to the coalescing of microcracks and microvoids was also reported for ASTM A490 high-strength bolt steel, 25) S10C steel, 26) D6ac steel 27) and single crystal of pure iron. 28) The QC fracture surface consisted of several facets of approximately 1 to 5 μm in length surrounded by fragmentary tear ridges as indicated in Fig.…”

Section: Qc Crack Propagation Processsupporting

confidence: 53%

Crack Initiation and Propagation Behavior of Hydrogen-induced Quasi-cleavage Fracture in X80 Pipeline Steel with Stress Concentration

et al. 2021

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The processes leading to hydrogen-related fracture in X80 pipeline steel with a stress concentration have been investigated comprehensively through observations of fracture surfaces and subsidiary cracks, stress analyses, crack initiation and propagation analyses and crystallographic analyses of fracture surfaces. Fracture morphology showed quasi-cleavage (QC) fracture under various amounts of hydrogen. It was found that QC cracks initiated in hydrogen-charged specimens in an area ranging from the notch tip to 100 μm inside based on interrupted tensile tests until just before fracture strength. A fracture surface topography analysis (FRASTA) revealed that QC cracks initiated at the notch tip. A finite element analysis indicated that the equivalent plastic strain was maximum at the crack initiation site at the notch tip. A backscattered electron image showed that nanovoids of 50-250 nm in diameter were present near the initiation site. Regarding the crack propagation process, field emission scanning electron microscopy (FE-SEM), electron backscattered diffraction (EBSD) and FRASTA results indicated that some microcracks in ferrite grains coalesced in a stepwise manner and propagated. Trace analyses using EBSD revealed that the QC fracture surface consisted of {011} slip planes, {001} cleavage planes and non-specific index planes. These findings indicate that QC fracture initiated at the notch tip due to the interaction between dislocations and hydrogen associated with local plastic deformation, and propagated in a stepwise manner by coalescence through vacancies, nanovoids and microcracks on various planes associated with/without plastic deformation in ferrite grains.

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Section: Qc Crack Propagation Processsupporting

confidence: 53%

Crack Initiation and Propagation Behavior of Hydrogen-induced Quasi-cleavage Fracture in X80 Pipeline Steel with Stress Concentration

et al. 2021

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“…Quasi-cleavage has also been observed in other tempered martensitic or bainitic RPV steels (A533B, F82H, ESR HT-9 and A490 types) when tested using 4 point bending (Edsinger et al 1996(Edsinger et al , 1997Knott 1997;Odette 1994;Oyanagi et al 2002).…”

Section: Discussionmentioning

confidence: 81%

Low-temperature fracture mechanisms in a spheroidised reactor pressure vessel steel

2007

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The micromechanisms of fracture of a spheroidised A533B reactor pressure vessel steel over the temperature range of −190 • C to +60 • C were investigated by performing uniaxial tensile tests on double-notched cylindrical specimens. Failure was by quasi-cleavage at temperatures between −190 • C and −145 • C. Quasi-cleavage fracture surfaces are characterised by clusters of planar facets that are separated from other facets either by large voids or by clusters of microvoids. At temperatures between −145 • C and −25 • C failure was by mixed microvoid coalescence and cleavage while complete microvoid coalescence was observed at temperatures higher than −25 • C. Over the whole temperature range studied, fracture nucleation was either from large single voids or localised regions of microvoids.

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“…It was also reported that ASTM A490 steel for high-strength bolts changed into similar fracture modes because stable initial crack propagation in the grains was caused by film-like γ R on lath boundaries. 22) These observations indicate that hydrogen embrittlement susceptibility of the SUJ2 specimens involved γ R at crack initiation. In the next section, the effect of γ R on crack initiation and hydrogen embrittlement susceptibility of SUJ2 will be discussed.…”

Section: Hydrogen Embrittlement Susceptibility Of Suj2mentioning

confidence: 80%

Hydrogen Embrittlement and Local Characterization at Crack Initiation Associated with Phase Transformation of High-strength Steel Containing Retained Austenite

et al. 2018

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States of hydrogen present in high-strength steels for use as bearing steel SUJ2 and hydrogen embrittlement susceptibility were examined using thermal desorption analysis (TDA) and tensile tests. SUJ2 specimens containing the retained austenite phase (γ R ) in the martensitic phase exhibited three hydrogen desorption peaks in the TDA profile. Two of the peaks desorbed at higher temperatures decreased with a decreasing amount of γ R , indicating they corresponded to desorption associated with γ R . Fracture strength in the presence of hydrogen increased with a decreasing amount of γ R and with an increasing strain rate. For the specimens containing γ R and hydrogen, a flat facet at the crack initiation site and a quasi-cleavage (QC) fracture in the initial crack propagation area were observed on the fracture surface. Local characterization using electron back-scattered diffraction (EBSD) revealed that the flat facet on the fracture surface corresponded not to γ R but to strain-induced martensite. In addition, the facet was on the {112} plane of martensite, which is the slip plane or deformation twin plane of body-centered-cubic metals. The reason for high hydrogen embrittlement susceptibility of the specimens containing γ R was attributed to the straininduced phase transformation at the crack initiation site of the flat facet and in the initial crack propagation area of the QC fracture. Furthermore, the strain rate dependency of hydrogen embrittlement susceptibility is presumably ascribable to local plastic deformation, i.e., the interaction between dislocations and hydrogen.

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Development of Quasi-Cleavage Crack Leading to Fracture of Hydrogen Charged High Strength Steel.

Cited by 4 publications

References 0 publications

Crack Initiation and Propagation Behavior of Hydrogen-induced Quasi-cleavage Fracture in X80 Pipeline Steel with Stress Concentration

Crack Initiation and Propagation Behavior of Hydrogen-induced Quasi-cleavage Fracture in X80 Pipeline Steel with Stress Concentration

Low-temperature fracture mechanisms in a spheroidised reactor pressure vessel steel

Hydrogen Embrittlement and Local Characterization at Crack Initiation Associated with Phase Transformation of High-strength Steel Containing Retained Austenite

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