Macroscale Levels of Diagnosis of the Mechanical State of the Metal of High-Temperature Pipelines

Poyarkova, E.V.; Кузеев, И.Р.

doi:10.17122/ogbus-2015-4-283-312

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…Durability of dissimilar welded joints from steels in the low-cycle region was determined under cyclic elastoplastic loading [2,3]. As a test machine, the facility of IR 5113-100 was used.…”

Section: Materials and Methods Of Researchmentioning

confidence: 99%

“…Cyclic loading of the sample to the level of accumulated damage Ni/Np=0.2 leads to the appearance of bundles clearly visible in the investigated region with an increase of 200x. They have the form of transverse grooves (dips), the formation of which is associated with the presence of elongated nonmetallic inclusions in the type of sulphides [13]. A small fraction of the surface of the fracture is occupied by large pits, in which particles of the sulfide type and of oxides of various sizes also found.…”

Section: Analysis Of Structural Changes Of Dissimilar Welded Joints Umentioning

confidence: 99%

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The evolution of the welded joints structure at low cycle fatigue

Poyarkova

Кузеев

2017

MATEC Web Conf.

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Abstract. The effect of cyclic damage on the structure evolution and the change in the micro stresses of the crystal cell in characteristic zones of dissimilar welded joints of steels strength classes Х60 and Х70 is estimated. It is shown, that with increase in the number of loading cycles in less strong metal of the welded joint, relaxation of internal stresses, realized by splitting individual ambits of ferrite grain or by the initiation of micro cracks, is observed. The results of fractographic analysis of a less reliable weld zone at different levels of samples fractures of accumulated damage are presented.

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Section: Materials and Methods Of Researchmentioning

confidence: 99%

Section: Analysis Of Structural Changes Of Dissimilar Welded Joints Umentioning

confidence: 99%

The evolution of the welded joints structure at low cycle fatigue

Poyarkova

Кузеев

2017

MATEC Web Conf.

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“…Èçâåñòíî, ÷òî â ïðîöåññå ýêñïëóàòàöèè ñòàëüíûõ òðóáîïðîâîäîâ ïðîèñõîäèò èçìåíåíèå, äðåéô, õàðàêòåðèñòèê ìàòåðèàëîâ. Ñóùåñòâóåò îáøèðíàÿ ëèòåðàòóðà, ïîñâÿùåííàÿ ýòîé ïðîáëåìå ó òðóá íåôòå-ãàçîòðàíñïîðòíîãî êîìïëåêñà è òåõíîëîãè÷åñêèõ òðóáîïðîâîäîâ, â ÷àñòíîñòè [2,3,[5][6][7][8][9][10].…”

Section: ââåäåíèåunclassified

Drift of mechanical characteristics of Common Rail fuel lines during operating time

Sveshchinskij¹,

О²

2019

Traktory i sel hozmashiny

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During the operation of steel pipelines, there is a change, drift, in the characteristics of the materials from which they are made. In the field of technological pipelines and oil and gas complex pipelines, an extensive literature is devoted to this issue, including both scientific publications and regulatory state and industry documents. Changes in the material characteristics of high pressure fuel lines of internal combustion engines did not attract the attention of specialists. Fuel lines were an important component of engines, but at that injection pressure level, materials and technologies, which determine, inter alia, the cost of a component in the total cost of the engine, they remained outside the area of special attention. The development in Russia of its own production of Common Rail systems makes it necessary to study the behavior of parts under conditions of prolonged loading with an internal hydraulic pressure of 1600 kg/cm2 and higher. The drift of the characteristics of the materials of the high pressure fuel lines can be of great importance, in terms of the reliability of the fuel system and the whole engine. For the first time, studies were carried out of the mechanical characteristics of seamless steel pipes at various operating times on a non-motorized test bench under loading with an internal hydraulic pressure of 1600 kg/cm2 with a pulsation frequency of 45-55 Hz. It has been established that during running hours, the hardness in the cross sections of the fuel lines increases. The standard deviation of hardness values also increases, i.e. the spread of values is present. The nature of the change in the tensile strength and yield strength with an operating time of more than 1100 hours requires additional research. It is concluded that it is necessary to test a larger number of samples on the engine to find out the limiting values of the mechanical characteristics of the material.

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“…Structural state of each particular welded joint and properties of the metal of its local areas acquired during the performance of fixed joint (welding) was assessed by metallographic studies of the structure of its reference zones by scanning electron microscopy, the obtained results of which are provided in [1][2][3][4]. The microstructures were obtained by means of electron microscope JEOL JSM-6460LV with the addition of energy-dispersive analysis INCA-energy under accelerating voltage of 25 kV.…”

Section: Introductionmentioning

confidence: 99%

Multifractal Parametrization of Welded Joints Structure as an Instrument of Diagnostics and Detection of Defects

Poyarkova

Кузеев

2017

SSP

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In each particular material the hierarchical peculiarities of defects indicate the corresponding hierarchical peculiarities of mechanisms of damage and limit states accumulation. In accordance with the points of view of V.S. Ivanova, V.V. Bolotin, A.A. Shanyavsky, L.I. Tushinsky, O.B. Naymark, V.V. Lepov, A.A. Bataev, the occurrence of the limiting state on a particular structural level is possible in case of accumulation on it of the ultimate concentration of defects of a certain kind. In such case the “established system” gets a new, additional degree of freedom, which promotes change of the prevailing mechanism of damage accumulation. The acceptability of this concept has been previously determined for a limited range of materials, which usually don’t have evident structural and mechanical heterogeneity. Thus, the extension of available results to the structurally heterogeneous materials and especially to the welded joints of such materials turned out to be a very difficult task. However, the concept of maximum (critical) level of damage accumulation on a particular scale level was introduced not so long ago. When assessing structural and mechanical heterogeneities of the structural material, an important role is played by concepts of similarity of mechanical phenomena, self-similarity of deformation and destruction processes and by the scale factor of reliability, which are considered in their historical development as a part of application of fractal concepts in the materials science. The application of complex synthesized approach (consisting of a set of diagnostic methods in the form of scanning electron microscopy and multifractal parametrization of materials microstructures) for detection of potentially hazardous zones of welded joints with the highest level of structural and mechanical heterogeneity was the main ideology of our study. In order to establish the cause-and-effect relationships of appearance of “macro-corrugations” on the surface of the material, the analysis of the structure of heterogeneous welded joints represented as a hierarchically organized system was performed.

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Macroscale Levels of Diagnosis of the Mechanical State of the Metal of High-Temperature Pipelines

Cited by 3 publications

References 2 publications

The evolution of the welded joints structure at low cycle fatigue

The evolution of the welded joints structure at low cycle fatigue

Drift of mechanical characteristics of Common Rail fuel lines during operating time

Multifractal Parametrization of Welded Joints Structure as an Instrument of Diagnostics and Detection of Defects

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