Degradation and reduction of small punch creep life of service-exposed Super304H steel
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To ensure the safety and structural integrity of a power boiler in thermal power plants, residual life management of superheater tubes at elevated temperature is needed. Over the decades, small punch (SP) creep testing has been widely used as an effective method for measuring creep life and creep properties of the boiler tube materials. In this study, a series of SP creep tests were performed at 650 °C with virgin and service-exposed Super304H stainless steels. The service period was 54750 h and 68550 h, respectively. The residual creep rupture life of the 68550 h serviced Super304H material decreased significantly when it was compared with the virgin and 54750 h serviced materials. Coarsening of the M23C6 precipitates along the grain boundaries made the adjacent region Cr-depleted, which could accelerate the formation of creep cavities at the grain boundaries. These microstructural degradations reduced the creep rupture life of the service-exposed materials. The Larson–Miller curve and the Monkman–Grant relationship were applied to predict the creep rupture life of service-exposed Super304H steels from the measured short creep rupture data.
KeywordsSuper304H Small punch creep Creep life Precipitate Degradation Superheater tube
Small punch creep coefficient
Small punch creep exponent
Monkman Grant constant
Larson Miller constant
Larson Miller parameter
Small punch load
Time to rupture (in hours)
Temperature (in Kelvin)
Minimum punch-displacement rate
Monkman-Grant exponent for small punch creep
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This work was supported by a Korea Institute of Energy Technology Evaluation and Planning (KETEP) [grant number 2014 1010101850] funded by the Ministry of Trade, Industry and Energy (MOTIE). This study was also supported by a KETEP [grant number 2016 1110100090] funded by the MOTIE.
- F. D. Persio, G. C. Stratford and R. C. Hurst, Validation of the small punch test as a method for assessing ageing of a V modified low alloy steel, Proc. of the Baltica VI International Conference on Life Management and Maintenance for Power Plants, Helsinki, Finland, 2 (2004) 523–535.Google Scholar
- ASTM A213/213M: Standard Specification for Steamless Ferritic and Austenitic Alloy-steel Boiler, Superheater, and Heat-exchanger Tubes, ASTM International (2003).Google Scholar
- V. Makarevičius, V. Baltušnikas, I. Lukošiūtė, R. Kriūkienė and A. Grybėnas, Transformation kinetic of M23C6 carbide lattice parameters in ferritic-martensitic P91 steel during thermal ageing, Proc. of Metal, Brno, Czech Republic (2015) 2–6.Google Scholar
- S. Yamasaki, Modelling precipitation of carbides in martensitic steels, Doctoral Thesis, University of Cambridge, UK (2004).Google Scholar
- K. C. Sahoo, S. Goyal, V. Ganesan, J. Vanaja, G. V. Reddy, P. Padmanabhan and S. K. Laha, Analysis of creep deformation and damage behaviour of 304HCu austenitic stainless steel, Materials at High Temperatures (2019) 1–16.Google Scholar
- C. Y. Chi, H. Y. Yu, J. X. Dong, W. Q. Li, S. C. Cheng, Z. D. Liu and X. S. Xie, The precipitation strengthening behavior of Cu-rich phase in Nb contained advanced Fe-Cr-Ni type austenitic heat resistant steel for USC power plant application, Progress in Natural Science: Materials International, 23 (3) (2012) 175–185.CrossRefGoogle Scholar