Influence of the long-term operation of 12Kh1M1F steel from different zones of a bend of steam pipeline of a thermal power plant on its mechanical characteristics

Student, О. Z.; Svirs’ka, L. M.; Dzioba, Ihor

doi:10.1007/s11003-012-9498-6

Cited by 12 publications

(5 citation statements)

References 7 publications

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“…Modern technologies of production and inspection do not allow the presence of crack-type defects in newly manufactured components. However, during long-term operation in conditions of cyclic loads and environmental impact, cracks in the elements may arise and develop from microstructural defects (e.g., from particles of large inclusions) [1,2]. A particularly high risk of initiation and development of cracks in a component is found when inclusions are grouped in one plane, which leads to the development of internal delamination cracks [3,4,5,6].…”

Section: Introductionmentioning

confidence: 99%

Fracture Mechanisms of S355 Steel—Experimental Research, FEM Simulation and SEM Observation

Dzioba

Lipiec

2019

Materials

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In this study, the fracture mechanisms of S355 ferritic steel were analyzed. In order to obtain different mechanisms of fracture (completely brittle, mixed brittle and ductile or completely ductile), tests were carried out over a temperature range of −120 to +20 °C. Our experimental research was supplemented with scanning electron microscopy (SEM) observations of the specimens’ fracture surfaces. Modeling and load simulations of specimens were performed using the finite element method (FEM) in the ABAQUS program, and accurate calibration of the true stress–strain material dependence was made. In addition, the development of mechanical fields before the crack tip of the cracking process in the steel was analyzed. The distributions of stresses and strains in the local area before the crack front were determined for specimens fractured according to different mechanisms. Finally, the conditions and characteristic values of stresses and strains which caused different mechanisms of fracture—fully brittle, mixed brittle and ductile or fully ductile—were determined.

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Section: Introductionmentioning

confidence: 99%

Fracture Mechanisms of S355 Steel—Experimental Research, FEM Simulation and SEM Observation

Dzioba

Lipiec

2019

Materials

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“…The knowledge of the actual creep strength of the material and the welded joint after service is crucial in determining the further safe operation time of the pipeline for the defined parameters of further work. A significant issue in the assessment of the condition of steam pipelines is also the knowledge of the creep strength of the repair welded joints, understood as rejoining of the materials serviced earlier in creep conditions [11,12].…”

Section: Introductionmentioning

confidence: 99%

The Influence Of Repair Welded Joint On The Life Of Steam Pipeline Made Of Cr-Mo Steel Serviced Beyond The Calculated Working Time

Zieliński¹,

Golański²

2015

Archives of Metallurgy and Materials

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The aim of the paper was to examine the influence of repair welded joints on the service life of steam pipelines for over 220 000 hours of service in creep conditions. The research included the study of the microstructure using scanning microscopy, the tests on mechanical properties at room and elevated temperature, determining the nil ductility transition temperature, and short-time creep tests to determine the residual life of the material. The tests allowed determining the time of further safe operation of elements of the steam pipeline with a repair welded joint, with reference to the base material, and the welded joint after service. The assessment of residual life and disposable residual life, and at the same time determining the possible time of further safe operation, has an essential meaning in the case of elements serviced considerably beyond the calculated working time.Keywords: creeping, material diagnostics, welded joints after service, Cr-Mo steel, residual life Celem pracy było zbadanie wpływu naprawczych złączy spawanych na trwałość eksploatacyjną rurociągów pary przez ponad 220 000 godzin eksploatacji warunkach pełzania. Wykonano badania mikrostruktury z wykorzystaniem mikroskopii skaningowej, badania właściwości mechanicznych w temperaturze pokojowej i podwyższonej, wyznaczono temperaturę przejścia w stan kruchy, przeprowadzono skrócone próby pełzania celem wyznaczenia trwałości resztkowej materiału. Przeprowadzone badania pozwoliły na wyznaczenie czasu dalszej bezpiecznej eksploatacji elementów rurociągu pary z wykonanym naprawczym złączem spawanym w odniesieniu do materiału rodzimego i złącza spawanego po eksploatacji. Ocena trwałości resztkowej i resztkowej trwałości rozporządzalnej, a tym samym oszacowanie lub wyznaczenie możliwego czasu dalszej bezpiecznej eksploatacji ma zasadnicze znaczenie w przypadku eksploatacji elementów znacznie poza obliczeniowy czas pracy.

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“…The accumulation of corrosion products (iron oxides and hydroxides) occupying a volume several times larger than the volume of the original iron [1] leads to the formation of internal stresses which results in cracking and spalling of the concrete cover [2]. It was shown [3] that the increase in the volume of the rust product associated with the reduction in the diameter of reinforcement (as small as 10-50 µm) may result in the initiation of cracks in concrete.Moreover, the degradation in wires may occur in the course of the long-term service, by analogy with the other steels [4,5], as a result of simultaneous action of the working stresses and the aggressive components of the surrounding environment (pore solutions in concrete). Thus, at appropriate potentials, chloride ions may induce local breakdown of the passive films formed in the pH 12.5 environments, and the pH value inside the pit may, therefore, fall down to low values because of hydrolysis [6].…”

mentioning

confidence: 99%

“…Moreover, the degradation in wires may occur in the course of the long-term service, by analogy with the other steels [4,5], as a result of simultaneous action of the working stresses and the aggressive components of the surrounding environment (pore solutions in concrete). Thus, at appropriate potentials, chloride ions may induce local breakdown of the passive films formed in the pH 12.5 environments, and the pH value inside the pit may, therefore, fall down to low values because of hydrolysis [6].…”

mentioning

confidence: 99%

Corrosion Resistance of Prestressing Steel Wires

Hredil

Toribio

2015

Mater Sci

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The cold-drawing process is widely used for the strengthening of wires made of pearlitic steels for reinforced-concrete structures. Then the steels undergo plastic deformation and the amount of defects increases. This could worsen their corrosion resistance. In our work, the effect of cold drawing on the electrochemical behavior of pearlitic steel in alkali and neutral environments is investigated. Under passivation conditions in the environment with рН 12.5, the changes in the properties of steel are not recorded. The decrease in polarization resistance and, therefore, the acceleration of corrosion as a result of the treatment of steel is observed only in the vicinity of the corrosion potential in a 3% NaCl solution.Prestressing steel wires are widely used in reinforced concrete. The formation of protective scales on wires in alkali concrete pore solutions and their properties depend on various factors, such as the composition and pH of solutions, their temperature, surface state, etc. The local depassivation of prestressing wires makes possible the start of the corrosion process in pits, which later can progress to the general corrosion. As a result, the effective cross-section of wires decreases and the cohesion between a wire and a concrete matrix weakens. The accumulation of corrosion products (iron oxides and hydroxides) occupying a volume several times larger than the volume of the original iron [1] leads to the formation of internal stresses which results in cracking and spalling of the concrete cover [2]. It was shown [3] that the increase in the volume of the rust product associated with the reduction in the diameter of reinforcement (as small as 10-50 µm) may result in the initiation of cracks in concrete.Moreover, the degradation in wires may occur in the course of the long-term service, by analogy with the other steels [4,5], as a result of simultaneous action of the working stresses and the aggressive components of the surrounding environment (pore solutions in concrete). Thus, at appropriate potentials, chloride ions may induce local breakdown of the passive films formed in the pH 12.5 environments, and the pH value inside the pit may, therefore, fall down to low values because of hydrolysis [6]. The fractographic analysis of the fracture surfaces of corroded prestressing wires shows that the brittle regions with cleavage appearance may form only as a result of the action of hydrogen at the crack tip [7]. The occurrence of hydrogen is possible due to the presence of free chlorides and the corrosion reaction, which provides the electrons required for the transformation of H + ions into atomic hydrogen, which then migrates into the crystal lattice of the metal.Under the same environmental conditions, the corrosion resistance of the metal itself becomes very important. The cold-drawing process noticeably changes the initial material and, finally, we obtain a material with different mechanical properties.It is important to clarify the influence of the cold-drawing process on the corrosion activity and ...

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Influence of the long-term operation of 12Kh1M1F steel from different zones of a bend of steam pipeline of a thermal power plant on its mechanical characteristics

Cited by 12 publications

References 7 publications

Fracture Mechanisms of S355 Steel—Experimental Research, FEM Simulation and SEM Observation

Fracture Mechanisms of S355 Steel—Experimental Research, FEM Simulation and SEM Observation

The Influence Of Repair Welded Joint On The Life Of Steam Pipeline Made Of Cr-Mo Steel Serviced Beyond The Calculated Working Time

Corrosion Resistance of Prestressing Steel Wires

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