Analysis of the Elastoplastic Deformation of the Material in the Process Zone

Panasyuk, V. V.; Ivanyts’kyi, Ya. L.; Maksymenko, O. P.

doi:10.1007/s11003-005-0095-9

Cited by 16 publications

(5 citation statements)

References 2 publications

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“…Values of true stresses S i in the zone of maximum strain were obtained by the formula: S i = P i /F i where F i –current values of the cross-sectional sample area, including the change in its (neck) diameter. The value of the true strain e in the local volume was calculated based on the data of displacements in two directions based on 0.5 mm using an ODIC [ 25 ].…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

“…The paper proposes an approach that involves using a non-contact method of control during the sample deformation in laboratory conditions and also provides an opportunity to control the most stressed areas of the structural element under operational conditions. In particular, the method of optical-digital correlation of images (ODIC) [ 25 , 26 ] makes it possible to control the sample deformation for a specific area and to determine the place where the stress-strain state is homogeneous from the point of view of the strain and stress distribution in the limited area. In addition, this method makes it possible to determine strain in two directions.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Hydrogen on the Fracture Resistance of Pre-Strained Steam Generator Steel 22K

et al. 2022

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In the paper, experimental studies of the hydrogen and pre-strained effect on fracture resistance of steam generator steel 22K were carried out. Special cylindrical samples were loaded up to fracture under a uniaxial tensile test with different pre-strained degrees and hydrogen charged times of the material. Stress-strain curves «Si–ei» were plotted. The true strain «ei» in the local volume was determined using the method of optical-digital image correlation (ODIC). The results showed that the hydrogen influence is practically absent in the elastic area of strain. The fracture energy of steel 22K decreases under the hydrogen influence and pre-strain in all investigated cases. It is shown that during six months of air exposure, with the 0% pre-strained samples release almost all hydrogen. In pre-strained samples, the hydrogen concentration decreased by 1–3% compared to the initial values. This indicates that they have trapped hydrogen that cannot escape on its own. Hydrogen embrittlement (HE) indexes for 0% pre-strained samples at different levels of hydrogen-charging calculated by the strain and energy approaches are equal to each other. There is a difference in the values of the HE index depending on the hydrogen-charge time for pre-strained samples. This indicates that both strain and strength characteristics of the material, which are integrally taken into account in the energy approach, are sensitive to HE.

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Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Hydrogen on the Fracture Resistance of Pre-Strained Steam Generator Steel 22K

et al. 2022

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“…In the process zone, by the method of digital correlation of images [19] and the corresponding program of calculations, for each level of loading (200, 400, 600 kg, etc. ), we determined the field of elastoplastic displacements in front of the crack tip.…”

Section: Hydrogen Concentration In the Process Zone Of A Hydrogenatedmentioning

confidence: 99%

Influence of the Stress-Strain State on the Distribution of Hydrogen Concentration in the Process Zone

et al. 2014

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We propose a theoretical-experimental approach to the determination of the concentration of hydrogen in the process zone. The plots of the dependences of the concentration of hydrogen on the mechanical characteristics of the material and external load are constructed.In the contemporary science, much attention is given to the development of the method aimed at the evaluation of the concentration of hydrogen in metals; in particular, in the process zone, where the material is deformed under stresses exceeding the yield strength. In [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], the influence of the stress-strain state on the distribution of hydrogen in the process zone was investigated in various specific cases. Formulation of the Problem and Its SolutionThe distribution of the concentration of hydrogen near the crack tip was found on the basis of the solution of the Fick equation, which takes into account the influence of the gradient of mechanical stresses on the diffusion of hydrogen in the process zone [12]:where C = C x, y, t ( ) is the hydrogen concentration,  ∇ = ∂/∂x, ∂/∂y ( ) is the Hamiltonian operator, D is the diffusion coefficient, R is the universal gas constant, T is absolute temperature, V H is the partial molar volume of hydrogen in the metal, σ h is the hydrostatic component of the stress tensor in the metal, and t is time.The Fick equation (1) is solved in a two-dimensional domain S (Fig. 1). In this case, it is assumed that the hydrogen distribution in the domain S is uniform and equal to C 0 . Hence, we use the following initial conditions for the distribution of hydrogen:(2)

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“…During loading, with a step of 250 kg the photos of area 3 × 4 mm at the crack tip were taken by CCD camera (resolution 640 × 480 px) equipped with a microscopic objective and the image capturing device National Instruments IMAQ PCI-1409. The obtained images were used for processing by the method of digital images correlation (DIC), with an accuracy of displacement evaluation ±1 px (0.006 mm) (Muravsky et al 2004;Panasyuk et al 2004). …”

Section: Testing Proceduresmentioning

confidence: 99%

“…For today many techniques for plastic zone size measurement are known (Uuz and Martin 1996), but a majority of them don't allow to determine the deformation distribution in this zone. A digital image correlation method (DIC) (Muravsky et al 2004;Panasyuk et al 2004) used in this paper allows us to do this with high accuracy. In many publications (Weber et al 2005;Yagodzinskyy et al 2010) it is shown, that hydrogen influences the material deformation in the crack tip as well as changes plastic zone form and size.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen influence on fracture of sheet carbon steel

et al. 2012

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Results of the researches of hydrogen influence on fracture of 65 sheet spring steel by several methods are presented. The distribution of deformation and topography of a hollow in front of the crack tip is determined, the stress intensity factor is calculated, fractographic analysis of a fracture surface and metallographic analysis of the morphology of crack distribution are carried out. The decrease of operation characteristics of the material as a result of hydrogen influence which becomes apparent in localization of plastic deformations and intensive delamination on the layers of rolling is established.

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Analysis of the Elastoplastic Deformation of the Material in the Process Zone

Cited by 16 publications

References 2 publications

Influence of Hydrogen on the Fracture Resistance of Pre-Strained Steam Generator Steel 22K

Influence of Hydrogen on the Fracture Resistance of Pre-Strained Steam Generator Steel 22K

Influence of the Stress-Strain State on the Distribution of Hydrogen Concentration in the Process Zone

Hydrogen influence on fracture of sheet carbon steel

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