The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
P Wang - One of the best experts on this subject based on the ideXlab platform.
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Lifetime Prediction of Steam Turbine Components under Multiaxial Thermo-Mechanical Fatigue Loading
Applied Mechanics and Materials, 2020Co-Authors: P WangAbstract:Lifetime prediction of steam Turbine Components under biaxial thermo-mechanical fatigue (TMF) loading of modern high chromium steel is prerequisite for design optimization. In this paper a phenomenological method which envelopes the synthesis of stress strain hysteresis loops and damage assessment under considering creep fatigue interaction is extended to multiaxial loadings. It is proposed as a post processing step depending on the results of a preceding finite element analysis based on a constitutive material model. Recalculation of biaxial service-type experiments on cruciform specimen of modern high chromium rotor steel 10CrMoWVNbN shows satisfactory results for lifetime estimation.
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two lifetime estimation models for steam Turbine Components under thermomechanical creep fatigue loading
International Journal of Fatigue, 2014Co-Authors: P WangAbstract:Abstract The flexibility of steam Turbine Components is currently a key issue in terms of the fluctuations in the power supply due to regenerative energy. Conventional steam power plants must run at varying utilization levels. Life estimation methods according to standards, e.g. ASME Code N47 and TR, assess the influences of creep and fatigue separately under the assumption of isothermal conditions at the maximum operating temperature. The influence of thermomechanical fatigue (TMF) loading still requires a significant number of experimental studies. Further, the interaction of creep and fatigue is not adequately taken into account. Thus, new lifetime estimation methods are required for the monitoring, re-engineering and new design of power plant Components. In this paper, both a phenomenological and a constitutive crack initiation lifetime estimation model for steam Turbine Components are introduced. The effectiveness of each method is shown by recalculation of uniaxial as well as multiaxial service-type creep–fatigue experiments on high-chromium 10%Cr stainless rotor steel. Finally, the two models are compared with respect to different aspects, such as the type and number of necessary experiments to determine model parameters, the prerequisite for the application and the limitations of each model.
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Two lifetime estimation models for steam Turbine Components under thermomechanical creep–fatigue loading
International Journal of Fatigue, 2014Co-Authors: P WangAbstract:Abstract The flexibility of steam Turbine Components is currently a key issue in terms of the fluctuations in the power supply due to regenerative energy. Conventional steam power plants must run at varying utilization levels. Life estimation methods according to standards, e.g. ASME Code N47 and TR, assess the influences of creep and fatigue separately under the assumption of isothermal conditions at the maximum operating temperature. The influence of thermomechanical fatigue (TMF) loading still requires a significant number of experimental studies. Further, the interaction of creep and fatigue is not adequately taken into account. Thus, new lifetime estimation methods are required for the monitoring, re-engineering and new design of power plant Components. In this paper, both a phenomenological and a constitutive crack initiation lifetime estimation model for steam Turbine Components are introduced. The effectiveness of each method is shown by recalculation of uniaxial as well as multiaxial service-type creep–fatigue experiments on high-chromium 10%Cr stainless rotor steel. Finally, the two models are compared with respect to different aspects, such as the type and number of necessary experiments to determine model parameters, the prerequisite for the application and the limitations of each model.
Dong Jin Kim - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid phase bonding of γ′- precipitation strengthened Ni based superalloys for repairing gas Turbine Components
Journal of Manufacturing Processes, 2017Co-Authors: Jeong Kil Kim, Hae Ji Park, Deog Nam Shim, Dong Jin KimAbstract:γ′-Precipitation strengthened Ni based superalloys are extensively being accepted for gas Turbine Components, because these material have excellent mechanical properties, as well as corrosion and oxidation resistance at high temperatures above 1000 °C. Transient liquid phase (TLP) bonding is an essential technique for gas Turbine component repair. In this article, TLP bonding characteristics of two types of γ′ precipitation strengthened superalloys − GTD111 solidified directionally and Udimet520 wrought − were investigated to approve this technique for the repair of Components. TLP bonding was carried out with an amorphous filler metal in various bonding conditions. The microstructural characterization of the joints was examined through optical microscopy (OM) and electron probe micro-analysis (EPMA). The experimental results showed clearly that TLP joints of these superalloys had different TLP bonding behaviors according to the bonding temperatures, and that microstructures such as dendritic structures and the melting points of the base metals had critical effects on these bonding behaviors.
Jeong Kil Kim - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid phase bonding of γ′- precipitation strengthened Ni based superalloys for repairing gas Turbine Components
Journal of Manufacturing Processes, 2017Co-Authors: Jeong Kil Kim, Hae Ji Park, Deog Nam Shim, Dong Jin KimAbstract:γ′-Precipitation strengthened Ni based superalloys are extensively being accepted for gas Turbine Components, because these material have excellent mechanical properties, as well as corrosion and oxidation resistance at high temperatures above 1000 °C. Transient liquid phase (TLP) bonding is an essential technique for gas Turbine component repair. In this article, TLP bonding characteristics of two types of γ′ precipitation strengthened superalloys − GTD111 solidified directionally and Udimet520 wrought − were investigated to approve this technique for the repair of Components. TLP bonding was carried out with an amorphous filler metal in various bonding conditions. The microstructural characterization of the joints was examined through optical microscopy (OM) and electron probe micro-analysis (EPMA). The experimental results showed clearly that TLP joints of these superalloys had different TLP bonding behaviors according to the bonding temperatures, and that microstructures such as dendritic structures and the melting points of the base metals had critical effects on these bonding behaviors.
Thomas E Strangmen - One of the best experts on this subject based on the ideXlab platform.
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resistance of silicon nitride Turbine Components to erosion and hot corrosion oxidation attack
1994Co-Authors: Thomas E StrangmenAbstract:Silicon nitride Turbine Components are under intensive development by AlliedSignal to enable a new generation of higher power density auxiliary power systems. In order to be viable in the intended applications, silicon nitride Turbine airfoils must be designed for survival in aggressive oxidizing combustion gas environments. Erosive and corrosive damage to ceramic airfoils from ingested sand and sea salt must be avoided. Recent engine test experience demonstrated that NT154 silicon nitride Turbine vanes have exceptional resistance to sand erosion, relative to superalloys used in production engines. Similarly, NT154 silicon nitride has excellent resistance to oxidation in the temperature range of interest - up to 1400 C. Hot corrosion attack of superalloy gas Turbine Components is well documented. While hot corrosion from ingested sea salt will attack silicon nitride substantially less than the superalloys being replaced in initial engine applications, this degradation has the potential to limit component lives in advanced engine applications. Hot corrosion adversely affects the strength of silicon nitride in the 850 to 1300 C range. Since unacceptable reductions in strength must be rapidly identified and avoided, AlliedSignal and the NASA Lewis Research Center have pioneered the development of an environmental life prediction model for silicon nitride Turbine Components. Strength retention in flexure specimens following 1 to 3300 hour exposures to high temperature oxidation and hot corrosion has been measured and used to calibrate the life prediction model. Predicted component life is dependent upon engine design (stress, temperature, pressure, fuel/air ratio, gas velocity, and inlet air filtration), mission usage (fuel sulfur content, location (salt in air), and times at duty cycle power points), and material parameters. Preliminary analyses indicate that the hot corrosion resistance of NT154 silicon nitride is adequate for AlliedSignal's initial engine applications. Protective coatings and/or inlet air filtration may be required to achieve required ceramic component lives in more aggressive environments.
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Resistance of Silicon Nitride Turbine Components to Erosion and Hot Corrosion/oxidation Attack
1994Co-Authors: Thomas E StrangmenAbstract:Silicon nitride Turbine Components are under intensive development by AlliedSignal to enable a new generation of higher power density auxiliary power systems. In order to be viable in the intended applications, silicon nitride Turbine airfoils must be designed for survival in aggressive oxidizing combustion gas environments. Erosive and corrosive damage to ceramic airfoils from ingested sand and sea salt must be avoided. Recent engine test experience demonstrated that NT154 silicon nitride Turbine vanes have exceptional resistance to sand erosion, relative to superalloys used in production engines. Similarly, NT154 silicon nitride has excellent resistance to oxidation in the temperature range of interest - up to 1400 C. Hot corrosion attack of superalloy gas Turbine Components is well documented. While hot corrosion from ingested sea salt will attack silicon nitride substantially less than the superalloys being replaced in initial engine applications, this degradation has the potential to limit component lives in advanced engine applications. Hot corrosion adversely affects the strength of silicon nitride in the 850 to 1300 C range. Since unacceptable reductions in strength must be rapidly identified and avoided, AlliedSignal and the NASA Lewis Research Center have pioneered the development of an environmental life prediction model for silicon nitride Turbine Components. Strength retention in flexure specimens following 1 to 3300 hour exposures to high temperature oxidation and hot corrosion has been measured and used to calibrate the life prediction model. Predicted component life is dependent upon engine design (stress, temperature, pressure, fuel/air ratio, gas velocity, and inlet air filtration), mission usage (fuel sulfur content, location (salt in air), and times at duty cycle power points), and material parameters. Preliminary analyses indicate that the hot corrosion resistance of NT154 silicon nitride is adequate for AlliedSignal's initial engine applications. Protective coatings and/or inlet air filtration may be required to achieve required ceramic component lives in more aggressive environments.
Deog Nam Shim - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid phase bonding of γ′- precipitation strengthened Ni based superalloys for repairing gas Turbine Components
Journal of Manufacturing Processes, 2017Co-Authors: Jeong Kil Kim, Hae Ji Park, Deog Nam Shim, Dong Jin KimAbstract:γ′-Precipitation strengthened Ni based superalloys are extensively being accepted for gas Turbine Components, because these material have excellent mechanical properties, as well as corrosion and oxidation resistance at high temperatures above 1000 °C. Transient liquid phase (TLP) bonding is an essential technique for gas Turbine component repair. In this article, TLP bonding characteristics of two types of γ′ precipitation strengthened superalloys − GTD111 solidified directionally and Udimet520 wrought − were investigated to approve this technique for the repair of Components. TLP bonding was carried out with an amorphous filler metal in various bonding conditions. The microstructural characterization of the joints was examined through optical microscopy (OM) and electron probe micro-analysis (EPMA). The experimental results showed clearly that TLP joints of these superalloys had different TLP bonding behaviors according to the bonding temperatures, and that microstructures such as dendritic structures and the melting points of the base metals had critical effects on these bonding behaviors.
