Damage Mechanisms Under Creep Fatigue Conditions in Alloy 800H

Author(s):  
B. Kempf ◽  
K. Bothe ◽  
V. Gerold
1990 ◽  
Vol 112 (1) ◽  
pp. 4-19 ◽  
Author(s):  
S. Y. Zamrik

Creep-fatigue interaction and its effect on damage of components in service have been a major concern to analysts. To deal with this problem, several criteria have been proposed and used, such as: cycle-time fraction summation rule, strain limit, fracture maps where damage mechanisms are based on crack initiation or propagation, and ductility exhaustion. These concepts are reviewed in this paper so that one can interpret the damage mechanisms caused by creep and by fatigue. If a long period of dwell-time at elevated temperature is imposed on a component under strain conditions, stress relaxation occurs. Relaxation data can be used, for example, in austenitic steels, in predicting creep stages; however, interpretation of data obtained from such tests could be misleading in assessing damage. An example is given for life prediction on the basis of two selected criteria: the fraction rule and ductility exhaustion.


Author(s):  
Heramb P. Mahajan ◽  
Tasnim Hassan

Abstract Current ASME Section III, Division 5 code provides elastic, simplified inelastic and inelastic analysis options for designing nuclear power plant components for elevated temperature service. These analyses methods may fail to capture the complex creep-fatigue response and damage accumulation in materials at elevated temperatures. Hence, for analysis and design of the nuclear power plant components at elevated temperature, a full inelastic analysis that can simulate creep-fatigue responses may be needed. Existing ASME code neither provides guidelines for using full inelastic analysis nor recommends the type of constitutive model to be used. Hence, a unified rate-dependent constitutive model incorporating a damage parameter will be developed, and its parameters for base metal will be determined. In addition, a full inelastic analysis methodology using this model to analyze the creep-fatigue performance of components for nuclear power applications will be developed. Base metal 800H (BM800H) data are collected from literature to determine constitutive material model parameters. The parameter determination methodology for a constitutive model is discussed. The optimized parameter set for BM 800H at different temperatures will be presented in the paper. Recommendations are provided on the constitutive model selection and its parameter determination techniques. In the future, this work will be continued for diffusion bonded Alloy 800H (DB800H) material, and obtained parameters will be compared.


2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Kee-Nam Song ◽  
Yong-Wan Kim

Evaluation of creep-fatigue damage has been carried out for the hot gas duct (HGD) structure in the nuclear hydrogen development and demonstration (NHDD) plant. The core outlet and inlet temperature of the NHDD plant are 950°C and 490°C, respectively. Case studies on high temperature design codes of the draft code case for Alloy 617, ASME boiler and pressure vessel code section III subsection NH (ASME-NH), and RCC-MR were carried out for the inner tube of the HGD for the candidate materials of Alloy 617 and Alloy 800H. Technical issues in application of the draft code case to a high temperature structure are discussed for the Alloy 617 material. Code comparison between the ASME-NH and RCC-MR for Alloy 800H has been carried out. The candidate material of the outer pressure boundary (cross vessel) of the HGD is Mod.9Cr-1Mo steel. The damage evaluation, according to the ASME-NH and RCC-MR for the cross vessel of Mod.9Cr-1Mo steel, has been conducted and their results were compared.


2019 ◽  
Vol 118 ◽  
pp. 8-21 ◽  
Author(s):  
Run-Zi Wang ◽  
Shun-Peng Zhu ◽  
Ji Wang ◽  
Xian-Cheng Zhang ◽  
Shan-Tung Tu ◽  
...  

Author(s):  
R. Viswanathan

Damage Mechanisms and Life Assessment of High-Temperature Components deals with the underlying causes of high-temperature failures and their effect on component life and reliability. The first few chapters develop the theory necessary to understand and analyze high-temperature damage phenomena, including fracture, creep, and fatigue. Various forms of embrittlement and corrosion are also addressed as are creep-fatigue, thermal fatigue, and welding defects. The chapters that follow discuss the practical implications of these phenomena, explaining how to assess damage and estimate the remaining service life of boiler tubes, turbine blades, reactor vessels, nozzles, and other components. Life-assessment procedures draw on a knowledge of design, material behavior, and nondestructive inspection techniques, which are covered as well. The book makes extensive use of data plots, diagrams, and images and includes many worked-out examples and case histories. It also serves as a ready source of material property data. For information on the print version, ISBN 978-0-87170-358-3, follow this link.


Author(s):  
Hyeong-Yeon Lee ◽  
Kee-Nam Song ◽  
Yong-Wan Kim

Evaluation of creep-fatigue damage has been carried out for the HGD (hot gas duct) structure in the NHDD (Nuclear Hydrogen Development and Demonstration) plant. The core outlet and inlet temperature of the NHDD plant are 950°C and 490°C, respectively. Case studies on high temperature design codes of the draft Code Case for Alloy 617, ASME-NH and RCC-MR were carried out for the inner tube of the HGD for the candidate materials of Alloy 617 and Alloy 800H. Technical issues in application of the draft Code Case to a high temperature structure are discussed for Alloy 617 material. Code comparison between the ASME-NH and RCC-MR for Alloy 800H has been carried out. The candidate material of the outer pressure boundary (cross vessel) of the HGD is Mod.9Cr-1Mo steel. The damage evaluation according to the ASME-NH and RCC-MR for the cross vessel of Mod.9Cr-1Mo steel has been conducted and their results were compared.


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