Effect of fracture mode on acoustic emission behavior in the hydrogen embrittled low-alloy steel

Merson, Evgeniy; Myagkikh, Pavel; Klevtsov, G. V.; Мерсон, Д. Л.; Vinogradov, Alexei

doi:10.1016/j.engfracmech.2018.05.026

Cited by 24 publications

(18 citation statements)

References 41 publications

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“…Some of the as-received bars were subjected to thermo-mechanical treatment through the following procedure: (1) homogenizing annealing at 810°C followed by quenching in water, (2) tempering at 450°C, (3) cold severe plastic deformation by the "CONFORM" ECAP (equal channel angular pressing) [12] process to 4 passes by the Bc route and (4) annealing at 350°C for residual stress removing. The chemical composition and mechanical properties of these as-received and ECAPed steels before and after hydrogen charging have been recently reported in [10] and are not discussed in the present paper. The flat rectangular specimens with 20 × 4 × 2.1 mm 3 dimensions were cut from the as-received and ECAPed bars by the electric-discharge machine and grounded by emery paper to the #240 grade.…”

Section: Methodsmentioning

confidence: 99%

“…A few publications concerning HE of UFG ferritic steels highlighted the detrimental effect of SPD grain refinement on their HE resistance [5,10,11], though some guidelines for improvement have been proposed too [5]. Tareda et al [11] found a significant increase in the HE susceptibility of ultra-low carbon interstitial free steel after SPD processing by accumulative roll-bonding.…”

Section: Introductionmentioning

confidence: 99%

“…Tareda et al [11] found a significant increase in the HE susceptibility of ultra-low carbon interstitial free steel after SPD processing by accumulative roll-bonding. Merson et al [10] showed that the ECAPed low-alloy steel grade 09G2S was much more susceptibility to HE than its as-received counterpart. Mine et al demonstrated that the reduced HE resistance of the Fe-0.01 % C alloy processed by SPD can be entirely recovered by annealing which results in the decrease of the dislocation density and low-angle grain boundaries serving as hydrogen traps [5].…”

Section: Introductionmentioning

confidence: 99%

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Effect of equal-channel angular pressing (ECAP) and current density of cathodic hydrogen charging on hydrogen trapping in the low-alloy steel

et al. 2020

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Owing to the outstanding mechanical properties, the steels and other metallic materials with the ultra-fine grained (UFG) microstructure obtained by severe plastic deformation (SPD) techniques such as equal channel angular pressing (ECAP) have been in the spotlight of the material science and engineering community over the last few decades. Nevertheless, the data on environmental effects such as stress-corrosion cracking and hydrogen embrittlement (HE) on the performance of the UFG ferritic steels is still limited and is awaiting for clarification and thorough comprehensive examination. In the present study, the effect of the current density of cathodic hydrogen charging on the hydrogen concentration and state in the ECAPed and as-received low-carbon steel grade 09G2S has been investigated by the hot-extraction gas-analysis. It is found that due to the increased dislocation density and the total length (or volume fraction) of grain boundaries the ECAPed steel occludes much more hydrogen than its as-received counterpart at the same hydrogen charging conditions. Besides, the hydrogen concentration in the ECAPed steel is significantly changed at current densities below 20 mA / cm 2 only and is not affected by hydrogen-induced cracking. In contrast, the non-monotonous growth of the hydrogen concentration in the as-received steel occurs at the increasing current density up to 340 mA / cm 2 and is controlled by the extent of hydrogen-induced damage.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of equal-channel angular pressing (ECAP) and current density of cathodic hydrogen charging on hydrogen trapping in the low-alloy steel

et al. 2020

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“…При этом наличие следов вязкого разрушения в изломе объясняется влиянием пластической деформации, сопровождающей процесс роста трещины. Другая точка зрения заключается в том, что рельеф квазискола может быть сформирован в результате вязкого разрушения [11,16,17]. Имеются сведения о том, что водород может облегчать подвижность дислокаций [18].…”

Section: Introductionunclassified

Effect of the stress-strain state on the path of quasi-cleavage hydrogen-assisted cracking in low-carbon steel

et al. 2021

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Сonflicting data on the effect of the stress-strain state on the shape and path of quasi-cleavage cracks in hydrogen-embrittled steels and iron have been reported in the literature recently. However, this issue is important for understanding the nature of hydrogen embrittlement (HE) and, particularly, the role of hydrogen in the mechanism of crack propagation. In this regard, in the present study, smooth and notched specimens of low-carbon steel were tensile tested with in-situ cathodic hydrogen charging. The side surface of the specimens fractured in this way was examined by scanning electron microscopy aiming at quantitative characterization of the length and curvature of secondary side surface cracks. In addition, fractographic analysis was performed. A great number of cracks having a characteristic S-shaped curved geometry are found on the side surface of the notched specimens. Moreover, the cracks can smoothly curve both on the scale of several grains as well as within the individual grain interior. In contrast, in the case of smooth specimens, the cracks generally exhibit relatively straight appearance. Quantitative analysis using a statistically-representative dataset has shown that, on average, the curvature of cracks in the notched specimens is significantly higher and is varied over a wider range of values than in the smooth specimens. Based on the data obtained, it is concluded that the path of quasi-cleavage cracks in hydrogen-embrittled ferritic and ferritepearlitic low-carbon steels is mainly determined by the characteristics of the stress-strain state, and not by the microstructure or crystallographic orientation of individual grains.

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“…Therefore, the manifestation of each AE wave reflects an irreversible change in the crystalline structure of the material. This is an active field of research [7]; however, in order to conduct such an analysis, proper detection and capture of every AE event is highly desirable.…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis of Acoustic Emission Hit Detection Methods Using Time Features

2019

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Acoustic emission (AE) analysis is a powerful potential characterization method for fracture mechanism analysis during metallic specimen testing. Nevertheless, identifying and extracting each event when analyzing the raw signal remains a major challenge. Typically, the AE detection is carried out using a thresholding approach. However, though extensively applied, this approach presents some critical limitations due to overlapping transients, differences in strength and low signal-to-noise ratio. In this paper, to address these limitations, advanced methodologies for detecting AE hits have been developed. The most prominent methodologies used are instantaneous amplitude, the short-term average to long-term average ratio, the Akaike information criterion, and wavelet analysis, each of which exhibits satisfactory performance and ease of implementation for diverse applications. However, their proneness to errors in the presence of non-cyclostationary AE wavefronts and the lack of thorough comparison for transient AE signals are constraints to the wider application of these methods in non-destructive testing procedures. In this paper, with the aim of making aware of the drawbacks of the traditional threshold approach, a comprehensive analysis of its limiting factors when taking into regard the AE waveform behavior is presented. In addition, in a second section, a performance analysis of the main advanced representative-methods in the field is carried out through a common comparative framework, by analyzing first, AE waves generated from a standardized Hsu-Nielsen test and second, a data frame of a highly active signal derived from a tensile test. In this paper, with the aim to quantify the performance with which these AE detection methodologies work, for the first time, time features as the endpoint and duration accuracies, as well as statistical metrics as accuracy, precision, and false detection rates, are studied.INDEX TERMS Acoustic emission, materials testing, AE thresholding method, short-term average to longterm average ratio, instantaneous amplitude, Akaike information criterion, wavelet analysis, Otsu's method.

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Effect of fracture mode on acoustic emission behavior in the hydrogen embrittled low-alloy steel

Cited by 24 publications

References 41 publications

Effect of equal-channel angular pressing (ECAP) and current density of cathodic hydrogen charging on hydrogen trapping in the low-alloy steel

Effect of equal-channel angular pressing (ECAP) and current density of cathodic hydrogen charging on hydrogen trapping in the low-alloy steel

Effect of the stress-strain state on the path of quasi-cleavage hydrogen-assisted cracking in low-carbon steel

Performance Analysis of Acoustic Emission Hit Detection Methods Using Time Features

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