The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform

Anna Vyrostkova - One of the best experts on this subject based on the ideXlab platform.

  • Evolution Of Cr-Mo-Vweld Metal Microstructure during creep Testing Part 2: P24 material
    Welding in the World, 2011
    Co-Authors: Stan T. Mandziej, Anna Vyrostkova, Mojca Solar
    Abstract:

    In the course of 5^thFP “SmartWeld” EU R&D project, welding consumables of P24 grade were developed with the aim of reaching adequate combination of creep strength and fracture toughness, eventually without post-weld heat treatment. All-weld metal samples, showing evidences of “smartness” in various creep Tests, were subjected to thorough metallographic and micro-analytical study, to explain changing of their properties. In particular, scanning and transmission electron microscope observations concentrated on evolution of microstructure and transformations of carbides, which were leading to nucleation of voids and cracks in various creep Tests. Three different types of creep Tests were carried out, i.e. the constant load short-term/ creep rupture Test, the small punch accelerated creep Test and the simulative (Gleeble) accelerated creep Test. The transformed microstructures after these creep Tests were compared with the initial microstructures of the weld metals. In this article are presented two different manual metal arc weld metals of P24 grade, in as-welded and post-weld heat-treated states, manufactured by Metrode Ltd, Chertsey, UK and by Elektrode, Jesenice, SI.

  • evolution of cr mo v weld metal microstructure during creep Testing part 1 p91 material
    Welding in The World, 2008
    Co-Authors: Stan T. Mandziej, Anna Vyrostkova
    Abstract:

    Weld metal samples, manufactured in the recently concluded EU project “SmartWeld”, were subjected to various creep Tests followed by thorough metallographic and micro-analytical investigations, in order to explain their properties and to predict their long-term behaviour. The microstructural study concentrated on evolution of microstructure and transformations of carbides, which were assisting nucleation of voids and cracks in the creep Tests. Results of the conventional constant load short-term/creep rupture Test were compared with results of the newly developed accelerated creep Test carried out on Gleeble physical simulator. The microstructures generated in these Tests were compared with the initial microstructures of the weld metals as well as with microstructures of exploited / crept materials. Most of the effort was dedicated to identification of precipitated phases, mainly carbides, as well as to their transformations. The metallographic study, mainly carried out by means of transmission electron microscopy on carbon extraction replicas and also by scanning electron microscopy on fractures with implementation of EDS x-ray microanalysis, was supplemented by Thermocalc calculations for the appearance of phases at equilibrium conditions. Then, using thin foil technique in TEM, the recovery and recrystallisation of the initial martensitic-bainitic microstructure of the weld metal matrix was studied and the formation of subgrains and grains observed. Finally, the changes in the substructure were correlated with nucleation of fractures/failure modes of various creep Tests. In general, the acceleration of creep-like transformation of microstructure appeared dependent on accumulated or localised strain exerted by the Testing method. Nevertheless, compatibility of the used Tests was confirmed with indication of several nuances affecting variations of the final micro-and sub-structures of the investigated weld metals after exposure to the creep Test conditions.

  • Evolution of Cr-Mo-V Weld Metal Microstructure During Creep Testing — Part 1: P91 Material
    Welding in the World, 2008
    Co-Authors: Stan T. Mandziej, Anna Vyrostkova
    Abstract:

    Weld metal samples, manufactured in the recently concluded EU project “SmartWeld”, were subjected to various creep Tests followed by thorough metallographic and micro-analytical investigations, in order to explain their properties and to predict their long-term behaviour. The microstructural study concentrated on evolution of microstructure and transformations of carbides, which were assisting nucleation of voids and cracks in the creep Tests. Results of the conventional constant load short-term/creep rupture Test were compared with results of the newly developed accelerated creep Test carried out on Gleeble physical simulator. The microstructures generated in these Tests were compared with the initial microstructures of the weld metals as well as with microstructures of exploited / crept materials. Most of the effort was dedicated to identification of precipitated phases, mainly carbides, as well as to their transformations. The metallographic study, mainly carried out by means of transmission electron microscopy on carbon extraction replicas and also by scanning electron microscopy on fractures with implementation of EDS x-ray microanalysis, was supplemented by Thermocalc calculations for the appearance of phases at equilibrium conditions. Then, using thin foil technique in TEM, the recovery and recrystallisation of the initial martensitic-bainitic microstructure of the weld metal matrix was studied and the formation of subgrains and grains observed. Finally, the changes in the substructure were correlated with nucleation of fractures/failure modes of various creep Tests. In general, the acceleration of creep-like transformation of microstructure appeared dependent on accumulated or localised strain exerted by the Testing method. Nevertheless, compatibility of the used Tests was confirmed with indication of several nuances affecting variations of the final micro-and sub-structures of the investigated weld metals after exposure to the creep Test conditions.

Stan T. Mandziej - One of the best experts on this subject based on the ideXlab platform.

  • Evolution Of Cr-Mo-Vweld Metal Microstructure during creep Testing Part 2: P24 material
    Welding in the World, 2011
    Co-Authors: Stan T. Mandziej, Anna Vyrostkova, Mojca Solar
    Abstract:

    In the course of 5^thFP “SmartWeld” EU R&D project, welding consumables of P24 grade were developed with the aim of reaching adequate combination of creep strength and fracture toughness, eventually without post-weld heat treatment. All-weld metal samples, showing evidences of “smartness” in various creep Tests, were subjected to thorough metallographic and micro-analytical study, to explain changing of their properties. In particular, scanning and transmission electron microscope observations concentrated on evolution of microstructure and transformations of carbides, which were leading to nucleation of voids and cracks in various creep Tests. Three different types of creep Tests were carried out, i.e. the constant load short-term/ creep rupture Test, the small punch accelerated creep Test and the simulative (Gleeble) accelerated creep Test. The transformed microstructures after these creep Tests were compared with the initial microstructures of the weld metals. In this article are presented two different manual metal arc weld metals of P24 grade, in as-welded and post-weld heat-treated states, manufactured by Metrode Ltd, Chertsey, UK and by Elektrode, Jesenice, SI.

  • evolution of cr mo v weld metal microstructure during creep Testing part 1 p91 material
    Welding in The World, 2008
    Co-Authors: Stan T. Mandziej, Anna Vyrostkova
    Abstract:

    Weld metal samples, manufactured in the recently concluded EU project “SmartWeld”, were subjected to various creep Tests followed by thorough metallographic and micro-analytical investigations, in order to explain their properties and to predict their long-term behaviour. The microstructural study concentrated on evolution of microstructure and transformations of carbides, which were assisting nucleation of voids and cracks in the creep Tests. Results of the conventional constant load short-term/creep rupture Test were compared with results of the newly developed accelerated creep Test carried out on Gleeble physical simulator. The microstructures generated in these Tests were compared with the initial microstructures of the weld metals as well as with microstructures of exploited / crept materials. Most of the effort was dedicated to identification of precipitated phases, mainly carbides, as well as to their transformations. The metallographic study, mainly carried out by means of transmission electron microscopy on carbon extraction replicas and also by scanning electron microscopy on fractures with implementation of EDS x-ray microanalysis, was supplemented by Thermocalc calculations for the appearance of phases at equilibrium conditions. Then, using thin foil technique in TEM, the recovery and recrystallisation of the initial martensitic-bainitic microstructure of the weld metal matrix was studied and the formation of subgrains and grains observed. Finally, the changes in the substructure were correlated with nucleation of fractures/failure modes of various creep Tests. In general, the acceleration of creep-like transformation of microstructure appeared dependent on accumulated or localised strain exerted by the Testing method. Nevertheless, compatibility of the used Tests was confirmed with indication of several nuances affecting variations of the final micro-and sub-structures of the investigated weld metals after exposure to the creep Test conditions.

  • Evolution of Cr-Mo-V Weld Metal Microstructure During Creep Testing — Part 1: P91 Material
    Welding in the World, 2008
    Co-Authors: Stan T. Mandziej, Anna Vyrostkova
    Abstract:

    Weld metal samples, manufactured in the recently concluded EU project “SmartWeld”, were subjected to various creep Tests followed by thorough metallographic and micro-analytical investigations, in order to explain their properties and to predict their long-term behaviour. The microstructural study concentrated on evolution of microstructure and transformations of carbides, which were assisting nucleation of voids and cracks in the creep Tests. Results of the conventional constant load short-term/creep rupture Test were compared with results of the newly developed accelerated creep Test carried out on Gleeble physical simulator. The microstructures generated in these Tests were compared with the initial microstructures of the weld metals as well as with microstructures of exploited / crept materials. Most of the effort was dedicated to identification of precipitated phases, mainly carbides, as well as to their transformations. The metallographic study, mainly carried out by means of transmission electron microscopy on carbon extraction replicas and also by scanning electron microscopy on fractures with implementation of EDS x-ray microanalysis, was supplemented by Thermocalc calculations for the appearance of phases at equilibrium conditions. Then, using thin foil technique in TEM, the recovery and recrystallisation of the initial martensitic-bainitic microstructure of the weld metal matrix was studied and the formation of subgrains and grains observed. Finally, the changes in the substructure were correlated with nucleation of fractures/failure modes of various creep Tests. In general, the acceleration of creep-like transformation of microstructure appeared dependent on accumulated or localised strain exerted by the Testing method. Nevertheless, compatibility of the used Tests was confirmed with indication of several nuances affecting variations of the final micro-and sub-structures of the investigated weld metals after exposure to the creep Test conditions.

Wang Yan-feng - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Microstructure Evolution on Property of P92 Steel During High-temperature Creep-Rupture Tests
    Journal of Chinese Society of Power Engineering, 2020
    Co-Authors: Wang Yan-feng
    Abstract:

    The microstructure of domestic P92 steel was investigated by SEM and TEM during Creep-Rupture Tests at 600 ℃,while the effect of microstructure evolution on its mechanical property analyzed.Results show that during the Creep-Rupture Tests,the hardness of P92 steel reduces before 1 429 h due to the coarsening of M23C6,and increases later on resulting from the precipitation of a large amount of Laves phase.With the coarsening of Laves phase,the hardness reduces again after Test duration of 6 063 h,when MX still keeps fine and has excellent precipitation strengthening effect.During the whole process of Creep-Rupture Test,the strengthening of dislocation and solid solution weakens due to both the recovery and recrystallization of lath martensite and the precipitation of Mo and W from the matrix.

  • Mechanical Properties and Microstructure Stability of T92 Steel Tubes After Long-term Exposure to High Temperatures
    Journal of Chinese Society of Power Engineering, 2020
    Co-Authors: Wang Yan-feng
    Abstract:

    Aging and Creep-Rupture Tests were carried out to domestic T92 steel tubes at 650 ℃ while study on corresponding microstructures performed.Results show that after having experienced aging at 650(°C) and Creep-Rupture Tests,following three phenomena may occur to the material: reduction of dislocation density,increase in sub-grain quantity and evolution of precipitates.After an aging time of 3 000 h,M_(23)C_6 precipitates will rapidly get coarsening while Laves phase form and get coarsening.M_(23)C_6 will stop growing and remain its morphology in the duration from 3 000 h to 10 000 h,due to precipitation and rapid coarsening of Laves phase from the matrix.Its martensite structure will still remain in lath morphology after aging up to 10 000 h,but partially transform to equiaxial sub-grains after Creep-Rupture Test.

Yoshikuni Kadoya - One of the best experts on this subject based on the ideXlab platform.

  • Study on Non-Destructive Evaluation of Material Damage Caused by High-Temperature Service. VII. Remaining Life Evaluation of High-Temperature Turbine Bolts.
    Journal of The Society of Materials Science Japan, 1992
    Co-Authors: Toshio Sakon, Yoshikuni Kadoya, Toru Goto, Shingo Date, Toru Matsuda, Yuji Sugita, Kenji Hattori
    Abstract:

    In order to improve the accuracy of remaining life evaluation for high-temperature bolts of 12Cr-Mo-W-V steel in long-time use, creep Tests on its notched specimens were carried out and non-destructive evaluation of creep damage for the bolt threads were investigated. Bending creep rupture Tests were also made for the bolt threads used for a long-time. The results obtained are as follows:(1) A bending creep rupture Test equipment was developed to obtain directly the creep life expenditure of bolts. Specimens were taken from a bolt used over a long period and bending creep Tests were carried out using this equipment. The results showed that the creep life expenditure of this bolt was small.(2) The creep void observation, hardness, eddy current and X-ray diffraction methods were applied to creep damage evaluation. In these methods except for the eddy current method, a good correlation was confirmed between the detected values and creep life expenditure. The creep void observation is considered as the most suitable method from the viewpoint of evaluation accuracy and applicability to the bolt threads.

  • Assessment of remaining life of fossil power plant parts by means of a miniature creep rupture Test.
    Isij International, 1990
    Co-Authors: Yoshikuni Kadoya, Toru Goto, Shingo Date, Takayoshi Yamauchi, Tomikane Saida, Tetsuro Sada
    Abstract:

    In order to validate a procedure for creep rupture Tests using miniature specimens, a sampling technique and a method of making the miniature specimens were investigated. Finally, the use of the iso-stress creep rupture Test on the miniature specimens to predict the remaining creep life of Cr-Mo-V, 21/4Cr-Mo and 11/4-1/2Mo steel was examined.The creep curve, rupture life and ductility of the miniature specimens Tested in argon were similar to those of conventional sized specimens in air. The fracture mode of the miniature specimens was also consistent with that of conventional sized specimens.On a graph showing temperature T vs. log time to rupture tr, the creep rupture data were represented with an iso-stress line, respectively. Each iso-stress line shifted parallel with the stress level.Moreover, the sampling device that was developed was applied to the operating plant components. Samples have been successfully removed from it and were obtained without affecting the material properties around the core hole.

Gui Li-cheng - One of the best experts on this subject based on the ideXlab platform.