Calibrating a ductile damage model for two pipeline steels: method and challenges

Depraetere, Robin; Cauwels, Margo; Waele, Wim De; Depover, Tom; Verbeken, Kim

doi:10.1016/j.prostr.2020.11.072

Cited by 3 publications

(4 citation statements)

References 10 publications

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“…The investigated material is a grade API 5L X70 [38] pipeline steel that had been in service for around 30 years. It was produced by a thermomechanically controlled rolling process (TMCP), resulting in a banded ferrite-pearlite microstructure and a notable degree of plastic anisotropy [39]. The microstructure is shown in Figure 1 and features MnS inclusions that are elongated in the longitudinal (L) and transverse (T) direction.…”

Section: Methodsmentioning

confidence: 99%

“…To track the deformation behavior of the specimens during tensile testing, the lateral contraction of the diameter in the transversal (T) and the through-thickness 235 (S) directions was monitored optically using the technique that is schematically shown in Figure 3 and is described in Depraetere et al [39]. By using two perpendicularly positioned cameras, both the post-necking behavior as well as the anisotropy of the material can 240 be evaluated during the test [43].…”

Section: Methodsmentioning

confidence: 99%

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Influence of stress triaxiality on hydrogen assisted ductile damage in an X70 pipeline steel

Depraetere

Waele

Cauwels

et al. 2023

Materials Science and Engineering: A

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Influence of stress triaxiality on hydrogen assisted ductile damage in an X70 pipeline steel

Depraetere

Waele

Cauwels

et al. 2023

Materials Science and Engineering: A

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“…During the test, the lateral contractions of the specimen were monitored using two perpendicularly positioned cameras. This technique is also described in [ 28 , 36 ]. After post-processing, the diameters in both the transversal-to-rolling T direction

and the through-thickness S direction

were extracted.…”

Section: Experimental Summarymentioning

confidence: 99%

“…Table 2 presents an overview of the experimental test data used for the calibration of the damage model parameters. Note that only a limited number of successful tests could be performed in the high triaxiality regime, since such a stress state leads to fracture of the micro-structural bands oriented along the S-direction, thus resulting in the occurrence of splits on the fracture surface that are accompanied by a sudden force drop [ 36 ]. The occurrence of a split is a stochastic event, and the cohesive strength of the interface between different layers is not included in the continuum HE model.…”

Section: Experimental Summarymentioning

confidence: 99%

Modeling of Hydrogen-Charged Notched Tensile Tests of an X70 Pipeline Steel with a Hydrogen-Informed Gurson Model

et al. 2023

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Hydrogen can degrade the mechanical properties of steel components, which is commonly referred to as “hydrogen embrittlement” (HE). Quantifying the effect of HE on the structural integrity of components and structures remains challenging. The authors investigated an X70 pipeline steel through uncharged and hydrogen-charged (notched) tensile tests. This paper presents a combination of experimental results and numerical simulations using a micro-mechanics-inspired damage model. Four specimen geometries and three hydrogen concentrations (including uncharged) were targeted, which allowed for the construction of a fracture locus that depended on the stress triaxiality and hydrogen concentration. The multi-physical finite element model includes hydrogen diffusion and damage on the basis of the complete Gurson model. Hydrogen-Assisted degradation was implemented through an acceleration of the void nucleation process, as supported by experimental observations. The damage parameters were determined through inverse analysis, and the numerical results were in good agreement with the experimental data. The presented model couples micro-mechanical with macro-mechanical results and makes it possible to evaluate the damage evolution during hydrogen-charged mechanical tests. In particular, the well-known ductility loss due to hydrogen was captured well in the form of embrittlement indices for the different geometries and hydrogen concentrations. The limitations of the damage model regarding the stress state are discussed in this paper.

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Effects of Temperature and Strain Rate on the Ductility of an API X65 Grade Steel

et al. 2022

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In the last few decades, great effort has been spent on advanced material testing and the development of damage models intended to estimate the ductility and fracture of ductile metals. While most studies focused on static testing are applied at room temperatures only, in this paper, multiaxial tests have been executed to investigate the effects of dynamic action and temperature on the mechanical and fracture behavior of an API X65 steel. To this end, a Split Hopkinson Bar (SHB) facility for dynamic tests, and a uniaxial testing machine equipped with a high-temperature furnace, were used. Numerical simulations of the experiments were setup for calibration and validation purposes. Based on the experimental results, the Johnson–Cook and Zerilli–Armstrong plasticity models were first tuned, resulting in a good experimental–numerical match. Secondly, the triaxiality and Lode angle dependent damage models proposed by Bai–Wierzbicki and Coppola–Cortese were also calibrated. The comparison of the fracture surfaces predicted by the damage models under different loading conditions showed, as expected, an overall significant increase in ductility with temperature; an appreciable increase in ductility was also observed with the increase in strain rate, in the range of low and moderate triaxialities.

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Calibrating a ductile damage model for two pipeline steels: method and challenges

Cited by 3 publications

References 10 publications

Influence of stress triaxiality on hydrogen assisted ductile damage in an X70 pipeline steel

Influence of stress triaxiality on hydrogen assisted ductile damage in an X70 pipeline steel

Modeling of Hydrogen-Charged Notched Tensile Tests of an X70 Pipeline Steel with a Hydrogen-Informed Gurson Model

Effects of Temperature and Strain Rate on the Ductility of an API X65 Grade Steel

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