Investigation into the Cyclic Strength of the Bodies of Steam Shutoff Valves from 10Kh9MFB-Sh Steel
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Steam shutoff valves are operated under complex loading conditions at thermal and nuclear power stations. In addition to exposure to high temperature and stresses resulting in fatigue, these valves are subjected to cyclic loads in heating-up–cooling down, opening–closing, etc. cycles. The number of these cycles to be specified in designing the valves should not exceed the maximum allowable value. Hence, the problem of cyclic failure rate of steam shutoff valve bodies is critical. This paper continues the previous publications about properties of the construction material for steam shutoff valve bodies (grade 10Kh9MFB-Sh steel) produced by electroslag melting and gives the results of investigation into the cyclic strength of this material. Fatigue curves for the steal used for manufacturing steam shutoff valve bodies are presented. The experimental data are compared with the calculated fatigue curves plotted using the procedures outlined in PNAE G-002-986 and RD 10-249-98. It is confirmed that these procedures may be used in designing valve bodies from 10Kh9MFB-Sh steel. The effect of the cyclic damage after preliminary cyclic loading of the specimens according to the prescribed load conditions on the high-temperature strength of the steel is examined. The influence of cyclic failure rate on the long-term strength was investigated using cylindrical specimens with a smooth working section in the as-made conditions and after two regimes of preliminary cyclic loading (training) at a working temperature of 570°C and the number of load cycles exceeding the design value, which was 2 × 103 cycles. The experiments corroborated that the material (10Kh9MFB-Sh steel) of the body manufactured by the method of electroslag melting had high resistance to cyclic failure rate. No effect of cyclic damages in the metal of the investigated specimens on the high-temperature strength has been found.
Keywords10Kh9MFB and 10Kh9MFB-Sh chromium steels electroslag melting shutoff valve body cyclic strength cyclic failure rate fatigue
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- 1.V. N. Skorobogatykh, L. Ya. Levkov, Yu. N. Kriger, I. A. Shchenkova, A. M. Bazhenov, D. A. Prudnikov, D. A. Shurygin, N. A. Babanin, and A. A. Karev, “Production process and property package of bodyblanks of DN 250 steam stop valves from 10H9MFB steel,” Tyazheloe Mashinostr., No. 6, 2–6 (2015).Google Scholar
- 2.L. Ya. Levkov, D. A. Shurygin, V. N. Skorobogatykh, I. A. Shchenkova, Yu. N. Kriger, A. M. Bazhenov, K. N. Utkina, and I. A. Ivanov, “Electroslag remelting as a promising direction for producing hollow and shaped objects of steel 10Kh9MFB-Sh,” Metallurg, No. 11, 48–53 (2016).Google Scholar
- 3.V. N. Skorobogatykh, I. A. Schenkova, I. A. Danyushevskiy, E. A. Grin’, L. Ya. Levkov, D. A. Prudnikov, D. N. Zhuravlev, and A. M. Bazhenov, “Application experience of grade 10Kh9MFB chromium steel for steam shutoff and control valve bodies,” Therm. Eng. 64, 272–279 (2017). doi 10.1134/S0040601517040085CrossRefGoogle Scholar
- 4.V. M. Goritskii and V. F. Terent’ev, Structure and Fatigue Failure (Metallurgiya, Moscow, 1980) [in Russian].Google Scholar
- 5.V. S. Ivanova and V. F. Terent’ev, Nature of Metal Fatigue (Metallurgiya, Moscow, 1975) [in Russian].Google Scholar
- 6.RD 10-249-98. Norms for Strength Calculation of Stationary Boilers and Pipelines for Cold Water and Steam (Nauchno-Tekh. Ts. Issled. Probl. Promyshl. Bezop., Moscow, 2010).Google Scholar
- 7.PNAE G-7-002-86. Norms for Strength Calculation of Equipment and Pipelines of Nuclear Power Installations (Energoatomizdat, Moscow, 1989).Google Scholar