STRUCTURAL CHANGES IN A RE-CONTAINING 10 %CR-3 %CO-3 %W STEEL UPON LONG-TERM AGEING AT 650 °C

1 NIKITIN Ivan
Co-authors:
1 FEDOSEEVA Alexandra 1 DUDOVA Nadezhda 1 KAIBYSHEV Rustam
Institution:
1 Belgorod National Research University, Belgorod 308015, Russia, fedoseeva@bsu.edu.ru
Conference:
28th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 22nd - 24th 2019
Proceedings:
Proceedings 28th International Conference on Metallurgy and Materials
Pages:
781-786
ISBN:
978-80-87294-92-5
ISSN:
2694-9296
Published:
4th November 2019
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
23 views / 8 downloads
Abstract

The application of new materials in the power units of new generation, which are able to work at ultra-supercritical parameters of steam (T ≥ 620-650 °С, Р = 25 - 35 MPa), can increase their efficiency up to 41-44 % and decrease the amount of harmful emissions. The aim of the present research was to investigate the major structural changes in new Re-containing steel during ageing at temperature of 650 °C. Structural changes in martensitic 10%Сr-3 %Co-3 %W-0.2 %Re steel during long-term ageing at 650 °C for about 13,600 h were investigated. This steel was solution treated at 1050 °C for 1 h, cooled in air, and subsequently tempered at 770 °C for 3 h. High thermal stability of tempered martensitic/ferritic lath structure is provided by a dispersion of fine M23C6 carbides precipitated during tempering and the Laves phase particles precipitated after 110 h of 650 °C aging. The precipitation of the Laves phase particles is accompanied with depletion of W atoms from the ferritic matrix. Moreover, decreasing W content in the ferritic matrix have a good correlation with increasing volume fraction of the Laves phase particles in the structure of the 10 %Сr-3 %Co-3%W-0.2 %Re steel during long-term ageing at 650 °C. The effect of Re addition on the kinetic of depletion of W from the solid solution and kinetic of precipitation Laves phase will be discussed.

Keywords: Martensitic steel, phase transformation, ageing, particles, microstructural evolution, precipitation
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