Effect of Microstructure on Cleavage Fracture of Thick-Section Quenched and Tempered S690 High-Strength Steel

Bertolo, Virgínia Morete Barbosa; Jiang, Quanxin; Walters, Carey L.; Pupovich, V.A.

doi:10.1007/978-3-030-36628-5_15

Cited by 5 publications

(8 citation statements)

References 9 publications

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“…Materials are extracted from the top quarter section and the middle section of plate. The materials have been previously characterized in Bertolo et al (2020). The chemical composition of the steel plate is shown in Table 2.…”

Section: Description Of the Materials And Mechanical Testsmentioning

confidence: 99%

“…12 and Table 4. Fractographic examinations reveal that the microstructural hard inclusions play an important role in the cleavage fracture process (Bertolo et al 2020).…”

Section: Description Of the Materials And Mechanical Testsmentioning

confidence: 99%

“…Although steels also have soft inclusions like MnS, they mostly affect the ductile failure mode and are not the focus in this paper. It has been observed that larger inclusions and inclusion clusters act as weakest features in the microstructure, allowing brittle crack initiation and propagation (Ghosh et al 2013;Popovich and Richardson 2015;Pallaspuro 2018;Bertolo et al 2020). The probability that cracks initiate in a given particle depends on the particle size, shape, volume fraction and orientation of the elongated particles with respect to the applied stress (Lindley et al 1970;Ray et al 1995;Bordet et al 2005;Chen et al 2010;Miao and Knott 2016).…”

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confidence: 99%

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Relating matrix stress to local stress on a hard microstructural inclusion for understanding cleavage fracture in high strength steel

et al. 2021

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Macroscale cleavage fracture toughness of high strength steels is strongly related to the fracture of hard microstructural inclusions. Therefore, an accurate determination of the local stress on these inclusions based on the matrix stress is necessary for the statistical modelling of macroscale cleavage fracture. This paper presents analytical equations to quantitatively estimate the stress of the microstructural inclusions from the far-field stress of the matrix. The analytical equations account for the inclusion shape, the inclusion orientation, the far-field stress state and matrix material properties. Finite element modelling of a representative volume element containing a hard inclusion shows that the equations provide an accurate representation of the local stress state. The equations are implemented into a multi-barrier model and compared with CTOD experiments with two different levels of constraint.

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Section: Description Of the Materials And Mechanical Testsmentioning

confidence: 99%

“…12 and Table 4. Fractographic examinations reveal that the microstructural hard inclusions play an important role in the cleavage fracture process (Bertolo et al 2020).…”

Section: Description Of the Materials And Mechanical Testsmentioning

confidence: 99%

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Relating matrix stress to local stress on a hard microstructural inclusion for understanding cleavage fracture in high strength steel

et al. 2021

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“…As a result, different phases, grain sizes, inclusions, phase fractions, and the presence of elemental segregation may be observed from the outer surface of the steel plate towards its centre. Consequently, a considerable through-thickness variation of mechanical properties is observed [1][2][3]. Although HSSs display the desired properties for structural applications, harsh service conditions (e.g.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive quantitative characterisation of the multiphase microstructure of a thick-section high strength steel

et al. 2022

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The through-thickness heterogeneous microstructure of thick-section high strength steels is responsible for the significant scatter of properties along the thickness. In this study, in order to identify the critical microstructural features in the fracture behaviour and allow for design optimisation and prediction of structural failure, the through-thickness microstructure of thick-section steels was extensively characterised and quantified. For this purpose, samples were extracted from the top quarter and middle thickness positions, and a combination of techniques including chemical composition analysis, dilatometry, and microscopy was used. The hardness variation through the thickness was analysed via micro-Vickers measurements and the local hardness variation in the middle section was studied via nanoindentation. The middle section presented larger prior austenite grain (PAG) sizes and larger sizes and area fraction of inclusions than the top section. Additionally, cubic inclusions were observed distributed as clusters in the middle, sometimes decorating PAG boundaries. Defects associated with the cubic inclusions or the interface between the matrix and the circular and cubic inclusions were observed in the mid-thickness. Moreover, the middle section presented long interfaces with the most significant hardness gradients due to the presence of hard centreline segregation bands. Hence, the microstructural and nanoindentation analyses indicated the middle section as the most likely area to have the lowest fracture toughness and, therefore, the most unfavourable section for fracture performance of the investigated S690QL high strength steel. The detrimental effect of the middle section was confirmed via CTOD tests where the middle presents lower fracture toughness than the top section.

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“…Studies have been conducted by many researchers through experiments that use the standard three-point bend specimen in the ductile-to-brittle transition or brittle region to investigate constraint effects on the fracture toughness 8 . As explained by Ruggieri 9 , the geometry of the specimen, which has a high ratio of crack depth and specimen height (a/W ≥ 0.5), can contribute to the stress triaxiality ahead of the crack front, as well as to the cleavage fracture conditions limiting the plasticity scale.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the Fracture Probability Parameters for Specimens Made by JIS SM490A Steel

et al. 2021

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This work established the fracture probability equation for JIS SM490A steel using the computational model supported by the local approach and the standard Crack Tip Opening Displacement (CTOD) fracture toughness experiments. As the experiments were conducted at a low temperature providing conditions for the brittle fracture, the specimen suffers a small plastic deformation until its failure. The computational model tries to represent the experiment results, estimating the scale and shape parameters of the Weibull distribution for the cumulative fracture probability equation. A procedure based on the local approach was executed to find the optimum values for the fracture probability equation. In addition, a plot was provided to show the distribution of likelihood values according to assumed values for the shape and scale parameters. In the end, a comparison between the experimental and predicted statistical distribution of critical CTOD was done successfully, indicating that material toughness can be predicted by the present model.

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Effect of Microstructure on Cleavage Fracture of Thick-Section Quenched and Tempered S690 High-Strength Steel

Cited by 5 publications

References 9 publications

Relating matrix stress to local stress on a hard microstructural inclusion for understanding cleavage fracture in high strength steel

Relating matrix stress to local stress on a hard microstructural inclusion for understanding cleavage fracture in high strength steel

A comprehensive quantitative characterisation of the multiphase microstructure of a thick-section high strength steel

Estimation of the Fracture Probability Parameters for Specimens Made by JIS SM490A Steel

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