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2020 №12 (07) DOI of Article
10.37434/as2020.12.01
2020 №12 (02)

Automatic Welding 2020 #12
Avtomaticheskaya Svarka (Automatic Welding), #12, 2020, pp. 3-16

Impact of technological parameters of arc deposition of an anti-corrosion layer in the vessel of WWER-1000 reactor on residual stress distribution

O.V. Makhnenko, O.S. Kostenevich
E.O. Paton Electric Welding Institute of the NAS of Ukraine. 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: office@paton.kiev.ua

Substantiation of extension of safe operating life of the vessels of WWER-1000 reactors in service requires taking into account the residual stresses, arising during fabrication as a result of heating at welding or surfacing and their redistribution after heat treatment. Automatic submerged-arc surfacing with strip electrodes was used for the cylindrical part of the vessels, and manual coated-electrode arc surfacing was applied for the nozzle zone surface (internal surface of nozzles Dn850 and their fillets), as well as other difficult-of-access places of the vessel. The process and parameters of the mode of anticorrosion arc surfacing can markedly influence the microstructural phase composition of the HAZ of base material, 15Kh2NMFA vessel steel, as well as residual stress distribution. Mathematical modeling was used for prediction of microstructural phase transformations in the HAZ at deposition of the protective anticorrosion layer; based on experimental welding thermokinetic diagram of austenite decomposition of 15Kh2NMFA vessel steel, distribution of residual stresses in WWER-1000 reactor vessel was derived, allowing for microstructural transformations at different technological modes of arc surfacing. Comparison of the results of residual stress distribution after deposition and heat treatment at different technological modes showed presence of a zone of compressives, which arise in the HAZ of 15Kh2NMFA steel, as a result of martensite-bainite transformation. 24 Ref., 6 Tabl., 15 Fig.
Keywords: reactor vessel, WWER-1000, anticorrosion arc surfacing, heat-treatment, residual stresses, microstructural phase transformations, mathematical modeling, thermokinetic diagram, 15Kh2NMFA steel


Received: 02.11.2020

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