Wyniki wyszukiwania - Biblioteka Nauki

1

Residual Life of Boiler Pressure Parts Made of the 13CrMo4-5 Steel after Long-Term Operation in a Creep Conditions

100%

Dziuba-Kałuża M. , Zieliński A. , Dobrzański J. , Sroka M. , Urbańczyk P. , Śliwa A.

Archives of Metallurgy and Materials

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2018

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tom Vol. 63, iss. 2

889--897

EN

This paper presents the method for determination of the time of further safe service for welded joints of boiler components after exceeding the design work time. The evaluation of the life of the parent material and its welded joints was performed. Microstructure investigations using a scanning electron microscope, investigations of strength properties, impact testing, hardness measurements and abridged creep tests of the basic material and welded joints were carried out. The investigations described in this paper allowed the time of further safe service of the examined components made of 13CrMo4-5 steel to be determined. The method for determination of the time of safe service of boiler components working under creep conditions allows their operation beyond the design service life. The obtained results of investigations are part of the materials database developed by the Institute for Ferrous Metallurgy.

2

The impact of repair welded joint on the life of Cr-Mo-V steel steam pipeline after service under creep conditions

72%

Zieliński A. , Dziuba-Kałuża M. , Dobrzański J. , Sroka M.

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2014

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tom Vol. 68, nr 1

36--44

EN

Purpose: The purpose of this paper was to examine the impact of repair welded joints on the life time of primary steam pipelines after more than 200 000 h service under creep conditions. Design/methodology/approach: The investigations of microstructure using scanning microscopy, investigations of mechanical properties at room and elevated temperature, determination of brittle fracture appearance transition temperature based on impact strength tests and abridged creep tests were carried out in order to determine the residual life of the material. Findings: The completed investigations allowed the time of further safe operation of the elements of primary steam pipeline with repair welded joint to be determined in relation to the parent material and welded joint after service. Practical implications: The assessment of residual life and disposable residual life, and thus the estimation or determination of possible time of further safe operation, is of the essence in case of operating the elements much beyond the design work time. Originality/value: The obtained results of investigations are the elements of material characteristics developed by the Institute for Ferrous Metallurgy for steels and welded joints made from them working under creep conditions.

3

Estimation of the residual life of L17HMF cast steel elements after long-term service

72%

Zieliński A. , Dobrzański J. , Golański G.

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tom Vol. 34, nr 2

137-144

EN

Purpose: of this paper is to present the changes of the mechanical properties and structure in material components of the power station boiler after long-term creep service made of G17CrMoV5-10 low-alloyed cast steel. Design/methodology/approach: The material of the research studies has been obtained from Polish power stations. Examined element has exceeded their assessed life of 105.000 hours. Mechanical properties and structure examinations were carried out on material after long-term service in creep conditions. The microstructure has been observed using a light and a scanning electron microscope. The investigation of the development of the precipitation processes was done by X-ray diffraction phase analysis. Findings: The microstructures and phase compositions of the residues, obtained from the elements, depend on life exhaustion extent. Practical implications: The presented method can be used for evaluation and qualification of structural changes in power station boiler and turbine components operating in creep conditions. Originality/value: The paper presents results of changes in the mechanical properties, structure and in the precipitation processes which are applied to evaluation for the condition of the elements in further industrial service.

4

Mechanical properties and structure of the Cr-Mo-V low-alloyed steel after long-term service in creep condition

58%

Dobrzański J. , Zieliński A. , Krztoń H.

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2007

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tom Vol. 23, nr 1

39-42

EN

Purpose: of this paper is to present the changes of the mechanical properties and structure in material components of the power station boiler after long-term creep service made of Cr-Mo-V low-alloyed steel. Design/methodology/approach: The investigated material has been obtained from the Polish power stations. All examined elements have exceeded their assessed life of 100 000 hours. Mechanical properties and structure examinations were carried out on materials after long-term service in creep conditions. The microstructure have been observed using a light and a scanning electron microscope. The investigation of the development of the precipitation processes were done by X-ray diffraction phase analysis. Findings: Carbide precipitations evolution in correlation to the life exhaustion extent were presented. Residual life in creep short tests was done. Residual life in correlation to changes structure and developed of carbide precipitation processes were presented. Practical implications: The presented methods can be used for materials evaluation operating in creep conditions. Originality/value: The presented results changes in the mechanical properties, structure and in the precipitation processes are applied to evaluation of the condition of the elements in further industrial service.

5

Numerical simulation of the stress state of an erosion-worn tee of the main gas pipeline

58%

Doroshenko Y. , Zapukhliak V. , Grudz Y. , Poberezhny L. , Hrytsanchuk A. , Popovych P. , Shevchuk O.

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tom Vol. 101, nr 2

63--78

EN

Purpose: To investigate the strength of tees with regard to their erosion wear, it is necessary to consider the complex three-dimensional geometric shape of the erosion worn inner surface of the tee. In addition, the study of the strength of the erosion worn tees of the main gas pipelines is complicated by the occurrence of additional stresses caused by changes in the direction of movement of the gas stream, resulting in an uneven pressure distribution in the inner cavity of the tee, and the temperature difference in its walls. Design/methodology/approach: Methodology for complex numerical three-dimensional simulation of the stressed state of tees of the main gas pipelines, taking into account the gas-dynamic processes that occur in the places of these defects, erosion wear of the tee wall, temperature difference in the tee walls. Findings: The acceptable parameters of erosion defects of tees of gas pipelines, and residual life of tees with erosion defects of the wall should be determined. Research limitations/implications: The developed model does not take into account internal corrosion and corrosion products as an additional erosion factor. Further studies plan to develop a model of corrosion-erosion wear of pipeline elements. Practical implications: The developed technique allows determining the location of erosion defects, estimating the strength and determining the residual life of tees with erosion wear of the wall in order to ensure their reliability, to rank such defects according to the degree of danger, to determine which of them are critical and need an immediate repair. Originality/value: Based on the gas-dynamic processes occurring in the internal cavity of the main gas pipelines’ tees, the complex three-dimensional geometric form of wall erosion defects, and temperature difference, the technique of three-dimensional simulation of stress state of the main gas pipelines’ tees is developed