Interrelationship between Creep Deformation and Damage for Advanced Creep-Resistant Steels

2018 ◽  
Vol 774 ◽  
pp. 119-124
Author(s):  
Vàclav Sklenička ◽  
Květa Kuchařová ◽  
Marie Kvapilová ◽  
Luboš Kloc ◽  
Jiri Dvorak ◽  
...  
Keyword(s):  
Creep Deformation ◽  
Power Plants ◽  
Fracture Behaviour ◽  
Creep Data ◽  
Creep Life ◽  
Empirical Formulas ◽  
Deformation And Fracture ◽  
Creep Resistant Steels ◽  
Insight Into ◽  
Time Assessment

The components used in power plants generally operate at elevated and/or high temperature and are subjected to internal pressure. Under such conditions creep is of a great concern and there is an urgent demand for methods which can be used to predict the creep life. In this work, using our earlier published creep data for advanced creep-resistant T23 and P92 steels, the interrelationship between creep deformation and damage have been analysed by linking them to the identified acting mechanisms, in terms of empirical formulas for the fracture time assessment. The validity and the applicability of various formulas are examined with the objective to gain insight into the creep deformation and fracture behaviour of the steels under investigation.

Creep deformation and fracture behaviour of modified 9Cr-1Mo steel in flowing liquid sodium environment

2017 ◽  
Vol 702 ◽  
pp. 232-240 ◽  
Author(s):  
S. Ravi ◽  
J. Vanaja ◽  
V.D. Vijayanand ◽  
P. Rajasundaram ◽  
S. Vijayaraghavan ◽  
...  
Keyword(s):  
Creep Deformation ◽  
Fracture Behaviour ◽  
Liquid Sodium ◽  
Flowing Liquid ◽  
Deformation And Fracture

Creep Deformation Parameters and Creep Life of Gr.91

2013 ◽  
Author(s):  
Fujio Abe
Keyword(s):  
Creep Rate ◽  
Creep Deformation ◽  
Minimum Creep Rate ◽  
Creep Data ◽  
Creep Life ◽  
Deformation Parameters ◽  
Austenite Grain ◽  
Strain Data ◽  
Downward Deviation ◽  
Prior Austenite Grain

The correlation between the creep deformation parameters and creep life has been investigated for Gr.91 by analyzing creep strain data at 450 to 725 °C, 40 to 450 MPa and tr = 11.4 to 68,755 h in the NIMS Creep Data Sheet. The creep life tr is correlated with the time to minimum creep rate tm as t r = 3.7 t m . Taking the stress dependence of tm / tr into account, the creep life could be predicted more reliably. The minimum creep rate ε̇min depends on both the tm and the strain to minimum creep rate εm as ε . min = 0.54 ε m / t m . The εm is evaluated to be 0.02 to 0.03 at high stresses at each temperature but it decreases with decreasing stress at temperatures above 550 °C, suggesting that the creep deformation in the transient region becomes more inhomogeneous with decreasing stress probably due to localized creep deformation within 1 μm in the vicinity of prior austenite grain boundaries. The downward deviation takes place in the the tr versus ε̇min curves (Monkman-Grant plot). At the same ε̇min, both the εm and tm change upon the condition of tm ∝ εm as can be seen from the above equation. The decrease in εm with decreasing stress, corresponding to decreasing ε̇min, causes a decrease in tm, indicating the downward deviation of the tr versus ε̇min curves.

Microstructures of Grade 91 Steels Under Long-Term Creep Conditions

2018 ◽  
Author(s):  
Kenji Kako ◽  
Susumu Yamada ◽  
Masatsugu Yaguchi ◽  
Yusuke Minami
Keyword(s):  
Remaining Life ◽  
Martensitic Steels ◽  
Creep Data ◽  
Creep Life ◽  
Creep Tests ◽  
Microstructural Observation ◽  
Type Iv ◽  
Grade 91 ◽  
Term Creep

Type IV damage has been found at several ultra-supercritical (USC) plants that used high-chromium martensitic steels in Japan, and the assessment of the remaining life of the steels is important for electric power companies. The assessment of the remaining life needs long-term creep data for over 10 years, but such data are limited. We have attempted to assess the remaining life by creep tests and by microstructural observation of Grade 91 steels welded pipes which were used in USC plants for over 10 years. Following the results of microstructural observation of USC plant pipes, we find that microstructures, especially distribution of MX precipitates, have large effect on the creep life of Grade 91 steels.

Estimating Long Term Major Maintenance and Capital Spending Requirements of Trinidad’s Aging Power Plants

2006 ◽  
Author(s):  
Robert R. Richwine ◽  
Michael Joseph ◽  
Charles Huguenard ◽  
Hafeez Baksh ◽  
Mike Elenbass
Keyword(s):  
Power Plants ◽  
Probabilistic Approach ◽  
Risk Profile ◽  
Periodic Review ◽  
Total Cost ◽  
Financial Decisions ◽  
Capital Spending ◽  
Generation Company ◽  
Insight Into

This paper describes the process used by the Power Generation Company of Trinidad and Tobago (PowerGen) to estimate the range of major (expenditures greater than US$50,000) recurring and non-recurring costs that can be expected to be incurred from 2006–2025 by PowerGen’s three existing generating facilities: Port of Spain, Point Lisas and Penal. Since many of these Capital and O&M costs are not 100% certain, a probabilistic approach was used that incorporates a Monte Carlo methodology. The results of this approach allowed PowerGen to better understand the range of possible major capital and O&M expenditures that would likely be required over the next 20 years along with a quantification of the risk profile of those ranges. By adding these costs to the routine O&M costs, a total cost cash flow timeline was able to be developed that more realistically forecast the actual financial requirements of PowerGen’s power plants. Periodic review and updates of the data will also provide PowerGen with a continuing sound basis for long term technical and financial decisions. Additionally, a benchmarking analysis was performed that compared the reliability trends of similar but older technologies to those plants in PowerGen’s fleet in order to gain an insight into the reliability expectations for PowerGen plants over the next twenty years.

Short-Term Creep Data Based Long-Term Creep Life Predictability for Grade 92 Steels and Its Microstructural Basis

2018 ◽  
Vol 25 (3) ◽  
pp. 713-722 ◽  
Author(s):  
Seen Chan Kim ◽  
Jae-Hyeok Shim ◽  
Woo-Sang Jung ◽  
Yoon Suk Choi
Keyword(s):  
Creep Data ◽  
Creep Life ◽  
Short Term ◽  
Term Creep ◽  
Short Term Creep
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