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THE EFFECT OF SIGMA-PHASE FORMATION ON LONG-TERM DURABILITY OF SUPER 304H STEEL

1,2 HORVATH Jakub.
Co-authors:
3 KRAL Petr 1 JANOVEC Jiří 3 SKLENICKA Václav
Institutions:
1 Czech Technical University in Prague, Faculty of mechanical engineering, Department of materials engineering, Prague, Czech Republic, EU
2 UJP PRAHA a.s., Prague, Czech Republic, EU
3 Institute of physics of materials, Academy of sciences of the Czech Republic, Brno, Czech Republic, EU
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
505-510
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
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Abstract

This work presents results of the analysis of phases formed in a SUPER 304H steel during a medium-term static isothermal ageing (675 °C/15000 h). The investigations of the precipitates were especially focused on the occurrence of sigma-phase because its formation leads to the serious embrittlement.The evaluation and distribution of brittle sigma-phase were determined on macroscopic level by using light microscopy/colour etching. The microstructure was also investigated on microscopic level by scanning electron microscopes Tescan Lyra 3 and JEOL JSM 5410 equipped by electron backscatter diffraction unit and by transmission electron microscope Jeol 2100F. This work also investigates the effect of sigma-phase formation on the impact strength of an aged state of SUPER 304H steel. For comparison reasons the microstructure and the mechanical properties of the initial as-received) state were also investigated. It was found that the formation of brittle sigma-phase in the aged and therefore degraded microstructure led to the significant decrease of the impact strength. The influence of brittle sigma-phase on long-term durability of the degraded steel regarding its insufficient impact strength is discussed.

Keywords: austenitic steel, medium-term ageing, SUPER 304H, sigma-phase, impact strength

© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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