The Paton Welding Journal, 2019, #9, 8-17 pages
Journal The Paton Welding Journal
Publisher International Association «Welding»
ISSN 0957-798X (print)
Issue #9, 2019 (October)
Effect of cooling cycle of welding on structure-phase composition of 15Kh2NMFA steel
O.V. Makhnenko, V.A. Kostin, V.V. Zhukov and E.S. Kostenevich
E.O. Paton Electric Welding Institute of the NAS of Ukraine
11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: email@example.com
In the recent years, mathematical methods are widely used for prediction of microstructure-phase composition of structural steels under thermal effect. Using mathematical modeling based on existing parametric regression equations there was carried out prediction of microstructure-phase transformations in HAZ metal of base material (steel 15Kh2NMFA) of WWER-1000 reactor vessel in arc cladding of protective anti-corrosion layer as well as performed comparative analysis of modeling results with obtained experimental data of dilatometric and metallographic analysis. The comparison of results ensures formation of bainite-martensite structure in HAZ metal of WWER-1000 reactor vessel, however a value of content of martensite in calculation and experimental determination is significantly different. For calculation determination of content of structural constituents it is necessary to use the experimental CCT diagrams of undercooled austenite decay for characteristic welding/cladding thermal cycles, which do not have long-term heating or holding at austenitizing temperature and cooling takes place with variable rate. CCT diagrams of undercooled austenite for typical cooling rates 3–5 °C/s and two maximum temperatures of thermal cycle, namely 1000 and 1350 °C were experimentally plotted for adequate evaluation of microstructure composition in HAZ metal of vessel steel 15Kh2NMFA in welding/cladding. Obtained results can be used in calculation determination of residual stresses in WWER-1000 reactor vessel for grounding the extension of safe operation life. 32 Ref., 7 Tables, 12 Figures.
Keywords: WWER-1000 reactor vessel, steel 15Kh2NMFA, anti-corrosion cladding, microstructure transformations, mathematical modeling, dilatometry
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