PSI - Issue 36

V.V. Kharchenko et al. / Procedia Structural Integrity 36 (2022) 59–65 V. V. Kharchenko et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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4. Materials, equipment and specimens The analysis of methods for determining the mechanical characteristics from the data of measurements of hardness and indentation was performed using the results of investigations on the materials of NPP equipment, namely: • metal template cut of the pipeline element of Ø160×16 mm (steel 22K) ; • metal template cut of the dismantled coil of Ø630×25 mm (material – steel 16HS) with a welded connection of the inlet nozzle of valve 1RA30 600 to the pipeline of "fresh" steam from steam generator PG-3; • metal template cut of the shell of Ø3272×36 mm of the housing of the dismantled high -pressure heater HV 2500 97-10A (material – 09H2S steel); • metal template cut of the stud (material – steel 25Kh1MF); • metal template cut of the stud M60×495 mm (material – steel 38KhN3МFА) ; • metal template cut of the envelope of metal of the control welded joint main circulation pipelines of Ø990×70 mm (material – steel 10HN2MFA and clad – 08Kh18N10H2B) To determine the strength characteristics, the fivefold proportional cylindrical specimens in uniaxial tension were used complying with DSTU EN 10002-1 (2006). The tests were made using a universal servohydraulic Instron 8802 machine. The specimens for measuring hardness and indentation were rectangular. The Brinell hardness was measured according to DSTU ISO 6506-1 (2019) using a stationary hardness tester type TSh-2M. Instrumented indentation was performed according to the international standard ISO 14577-1 (2015) in cyclic loading mode with a 2.5 mm ball diameter using a UTM-20HT laboratory machine, developed by Katok et al. (2019). During indentation and hardness measurement, all the requirements for the test equipment were met. 5. Procedure analysis The analysis of normative documents on the determination of mechanical characteristics by hardness in Fig. 4 implies that none of them makes it possible to determine the characteristics of all the materials under investigation with a deviation less than that specified in the documents TPKM-10-01 (2001), SOU-N NAEK 133 (2016), RD EO 0027 (2005) and I 1.2.1.02.019.1121 (2016). In addition, for 09H2S and 25Kh1MF steels, there was no correlation in all the documents, except I 1.2.1.02.019.1121 (2016) for 09H2S steel.

а

b

Fig. 4. Comparison of the methods for determining the mechanical properties based on the Brinell hardness: (а) yield strength; (b) tensile strength (MPa).

The comparative analysis of the methods of determining the mechanical characteristics from the results of