Assessment of structural and mechanical heterogeneity of the material of turbine runners based on the results of hardness measurements

The article presents an assessment of the structural heterogeneity and mechanical properties of the turbine runners of hydroelectric power plants in the presence of operational defects based on the hardness measurements. The article presents the design features and structure of the turbine runner’s metal. The chemical composition of the steel was determined by laser spark emission spectrometry using a portable laser steeloscope. The mechanical properties were determined based on the static tension testing of the samples using an tensile testing machine. The impact work and impact toughness characteristics were obtained based on the impact bending testing of samples with a U-shaped concentrator using a pendulum impact test machine in the temperature range from +20 to –30°C. The crack resistance characteristics were obtained based on the crack resistance testing of samples using a testing machine. The samples for all tests were cut from a fragment of the turbine runner’s blade. The metal hardness values were obtained using the dynamic portable hardness tester by measuring the Brinell hardness on four blades from the non-pressure side in the areas of cavitation damage. The main problems of hydraulic turbine operation associated with cavitation damage to the metal are described. The division of the turbine runner’s blades into zones according to the degree of cavitation damage is shown. Based on the results of Brinell hardness measurements, the characteristics of mechanical properties — the yield strength and tensile strength — were calculated. Based on their values, statistical processing was made and histograms of distributions were constructed with the determination of the characteristic law of distribution of a random variable, the heterogeneity coefficients were determined and graphs of the statistical distributions of the values of the characteristics of mechanical properties were constructed.

1. Bryzgalov V. I., Klyukach A. A. Condition of the impellers of the Sayano-Shushenskaya HPP hydroelectric units and the main directions for maintaining their operability / Gidrotekhn. Stroit. 2000. No. 1. P. 26 – 29 [in Russian].

2. Aniskovich E. V., Moskvichev V. V., Chernyaev A. P. Analysis of the results of diagnostics the turbine runners of the Krasnoyarsk hydroelectric station with long operation life / Gidrotekhn. Stroit. 2019. No. 10. P. 19 – 27 [in Russian].

3. Sivkov V. G. Problems of crack formation in the blades of the impellers of the Sayano-Shushenskaya HPP hydroelectric units / Gidrotekhn. Stroit. 2003. No. 11. P. 51 – 52 [in Russian].

4. Gabaydulin D. Yu., Grechneva M. V. Resources to repaire hydroturbine blades affected by cavitation / Vestn. IrGTU. 2012. No. 12. P. 40 – 43 [in Russian].

5. Sokolkin Yu. V., Tashkinov A. A. Mechanics of Deformation and Fracture of Structurally Heterogeneous Bodies. — Moscow: Nauka, 1984. — 116 p. [in Russian].

6. Romanov A. N. Problems of materials science in mechanics of deformation and fracture at the stage of crack formation (Part 2). Structural and deformation heterogeneity of structural materials and dispersed crack formation / Vestn. Nauch.-Tekhn. Razv. 2014. Vol. 77. No. 1. P. 37 – 54 [in Russian].

7. Aniskovich E. V. An integrated approach to assessing the heterogeneity of mechanical properties in the metal of elements of loaded structures / VIII All-Russian Conference with international participation «Safety and monitoring of natural and man-made systems». — Novosibirsk: FRC IVT, 2023. P. 102 – 108 [in Russian]. DOI: 10.25743/ssts.2023.34.14.023

8. Granovsky S. A., Malyshev V. M., Orgo V. M., Smolyarov L. G. Designs and calculation of hydraulic turbines. — Leningrad: Mashinostroenie, 1974. — 408 p. [in Russian].

9. Osipok T. V., Zaides S. A. Evaluation of anisotropy of mechanical properties of carbon steel flat products / Vestn. IrGTU. 2020. Vol. 24. No. 5. P. 1007 – 1018 [in Russian]. DOI: 10.21285/1814-3520-2020-5-1007-1018

10. Volkova E. F., Mostyaev I. V., Akinina M. V. Comparative analysis of mechanical properties anisotropy and microstructure of semi-finished products from high-strength magnesium alloys with REE / Tr. VIAM. 2018. No. 5. P. 24 – 32 [in Russian]. DOI: 10.18577/2307-6046-2018-0-5-24-33

11. Aniskovich E. V. Integrated approach to assessing the heterogeneity of mechanical properties in the metal of elements of loaded structures / VIII All-Russian Conference with International Participation «Safety and Monitoring of Natural and Man-Made Systems». — Novosibirsk: FRC IVT, 2023. P. 102 – 108 [in Russian]. DOI: 10.25743/ssts.2023.34.14.023

12. Aniskovich E. V., Moskvichev V. V. Study of the characteristics of crack resistance of metal in zones of heterogeneity of randomly distributed mechanical properties / Scientific works of the 6th International Scientific and Technical Conference «Durability and Structural Materials Science» (ZhivKom-2022) / A. N. Romanov, Ed. — Moscow: IMASh RAS, 2022. P. 25 – 30 [in Russian].

13. Orlov A. I. On the requirements for statistical methods of data analysis (generalizing article) / Industr. Lab. Mater. Diagn. 2023. Vol. 89. No. 11. P. 98 – 106 [in Russian]. DOI: 10.26896/1028-6861-2023-89-11-98-106

14. Snegirev S. G. Statistical analysis and use of relationships between the physical and mechanical properties of steels and cast irons. — Minsk: Belarusian Science, 2021. — 145 p. [in Russian].

15. Mikhailov V. E., Khomenok L. A., Sudakov A. V., Obukhov S. G. On the issue of comprehensive diagnostics and examination of the condition of thermal power plants and hydroelectric power plants equipment / Reliability Safety Energy. 2010. No. 2. P. 9 – 14 [in Russian].

16. Ivanchenko I. P., Prokopenko A. N. Analysis operational materials about educational cracks on radial axial water turbine blades Krasnoyarsk hydropower station / Gidrotekhn. Stroit. 2019. No. 10. P. 6 – 18 [in Russian].

17. Aniskovich E. V., Moskvichev V. V., Makhutov N. A., et al. Evaluation of residual stresses in the blades of the impellers of hydraulic units / Gidrotekhn. Stroit. 2018. No. 11. P. 178 – 184 [in Russian].

18. Georgievskaya E. V. Hydroturbine lifespan — a guarantee of reliability and safety of hydroelectric power station operation. Analytical literature review. — LAP Lambert Academic Publishing, 2018. — 157 p. [in Russian].

19. Markovets M. P. Determination of mechanical properties of metals by hardness. — Moscow: Mashinostroenie, 1979. — 191 p. [in Russian].

20. Baryshev E. E. Mechanical properties of materials. Educational electronic textbook. — Yekaterinburg: USTU-UPI, 2008 [in Russian].

21. Bearing capacity and safety of metal-composite tanks of spacecraft / V. V. Moskvichev, N. A. Testoyedov, Eds. — Novosibirsk: Nauka, 2021. — 440 p. [in Russian]. DOI: 10.7868/978-5-02-041474-7

22. Aniskovich E. V., Moskvichev V. V., Chernyaev A. P. Assessment of the residual life of turbine runners with operational defectiveness / Industr. Lab. Mater. Diagn. 2023. Vol. 89. No. 6. P. 62 – 75 [in Russian]. DOI: 10.26896/1028-6861-2023-89-6-62-75

23. Moskvichev V. V., Makhutov N. A., Shokin Yu. I., et al. Applied problems of structural strength and fracture mechanics of technical systems. – Novosibirsk: Nauka, 2021. — 796 p. [in Russian]. DOI: 10.7868/978-5-02-038832-1

24. Georgievskaya E. V. Methodological foundations for predicting the resource of hydraulic turbines under long-term actual operation conditions / VIII All-Russian Conference with International Participation «Safety and Monitoring of Natural and Man-Made Systems». — Novosibirsk: FRC IVT, 2023. P. 46 – 51 [in Russian]. DOI: 10.25743/43/ssts.2023.48.85.009

25. Makhutov N. A., Gadenin M. M., Yudina O. N. Analysis of the cyclic strength of technical systems in conditions of complex operation loading / Industr. Lab. Mater. Diagn. 2023. Vol. 89. No. 10. P. 55 – 62 [in Russian]. DOI: 10.26896/1028-6861-2023-89-10-55-62