Automatic Welding, 2025, №04

2025 №04 (05)

2025 №04 (07)

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"Avtomatychne Zvaryuvannya" (Automatic Welding), #4, 2024, pp. 40-46

Influence of the structural phase state on the properties of welded joints of steam pipelines

V.V. Dmitrik, Chen Xinlei

National Technical University «Kharkiv Polytechnic Institute». 2 Kyrpychova Str., 61002, Kharkiv, Ukraine. E-mail: dmitrikvitali@gmail.com

The paper considers the peculiarities of the influence of the structural-phase state on the properties of welded joints of steam pipelines, as well as on their reliability and residual service life. The determination of physical and mechanical properties, reliability, and service life is mostly related to welded joints of those steam lines whose operating parameters are as follows: temperature of 545 °C, steam pressure of 25.5 MPa. It was found that with an increase in the operating time of welded joints, gradual transformation of the ferritic-bainitic structure into a ferritic-carbide mixture occurs in their structure, the amount of which increases accordingly. The presence of such a mixture ensures a decrease in the mechanical properties of the metal of welded joints and contributes to its damage by the brittle mechanism. The growth rate of the ferritic-carbide mixture largely depends on the initial structure of the welded joints. It was found that the presence of pearlite in the initial structure accelerates the formation of a ferritic-carbide mixture. 10 Ref., 1 Tabl., 12 Fig.
Keywords: structural-phase state, heat-resistant steels, reliability, service life, damageability, welded joints, sections of the heat-affected zone, ferritic-carbide mixture, mechanical properties


Received: 21.04.2024
Received in revised form: 30.06.2025
Accepted: 05.07.2025

References

1. Dmitrik, V.V., Sobol, O.V., Pogrebnoj, M.A., Glushko, A.V., Ishchenko, G.I (2015) Structural changes in metal of welded joints of steam pipelines in operation. The Paton Welding J., 12, 24–28. DOI: https://doi.org/10.15407/tpwj2015.12.05
2. Dmitrik, V.V., Kasyanenko, I.V., Latynin, Y.M. (2021) Structural condition and damage of metal of welded joints of steam pipelines. Avtomatychne Zvaryuvannya, 9, 38–42 [in Ukrainian]. DOI: https:// doi.org/10.15407/as2021.09.06
3. Dmytryk, V.V., Glushko, A.V., Poznyakov, V.D., Kasyanenko, I.V. (2023) Creep pores in welded joints. Strength of Materials, 55, 287–295. DOI: https://doi.org/10.1007/s11223-023-00523-6
4. Glushko, A.V., Dmitrik, V.V., Syrenko, T.A. (2018) Creep of welded joints of steam pipelines. Metallofizika i Noveishie Tekhnologii, 40(5), 683–700 [in Russian]. DOI: https://doi.org/10.15407/mfint.40.05.0683
5. Сhalko, L. (2024) Structural-phase characteristics of damage to welded joints of TPP steam pipelines from heat-resistant steels (Review). The Paton Welding J., 7, 10–16. DOI: https://doi.org/10.37434/ tpwj2024.07.02
6. Skulsky, V.Yu., Tsaryuk, A.K., Moravetsky, S.I. (2009) Evaluation of susceptibility of welded joints of heat-resistant chromium martensitic steel to cracking at heat treatment. The Paton Welding J., 1, 2–5.
7. Skulsky, V.Yu., Tsaryuk A.K. (2004) New heat resistant steels for manufacture of weldments in heat power units (Review). The Paton Welding J., 4, 32–37.
8. Skulsky, V.Yu. (2006) Features of δ-ferrite formation on the fusion boundary in welding heat resistant chromium martensitic steel. The Paton Welding J., 11, 13–16.
9. SOU 40.3-0013044-20:2010. Guideline. Assessment of the technical condition of metal of straight sections of the main steam lines of thermal power plants. Influence of process stoppages on changes in the technical condition of the metal in operation. Standard instruction. Lviv, SE «LKB» and FMI NASU [in Ukrainian].
10. DSTU EN 10216-2:2016 (EN 10216-2:2013, IDT). Seamless steel pipes for use under pressure. Technical conditions of delivery. Date of entry into force: 01.01.2017 [in Ukrainian].

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