THE INFLUENCE OF SIGMA PHASE PRECIPITATION ON MECHANICAL PROPERTIES OF TP347H AUSTENITIC STEELS AFTER 100.000 HOURS SERVICE IN COAL-FIRED POWER PLANT

1 KANDER Ladislav
Co-authors:
2 KORCAKOVA Leona
Institutions:
1 MATERIAL AND METALLURGICAL RESEARCH Ltd., Ostrava, Czech Republic, EU, ladislav.kander@mmvyzkum.cz
2 COW I/DTU MEK, Kgs. Lyngby, Denmark, EU, leko@cowi.dk
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:
693-698
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:
362 views / 174 downloads
Abstract

The Danish coal-fired Ultra Super Critical (USC) plant, Nordjyllandsværket has now reached 100.000 hours of operation. Taking advantage of the boiler maintenance programme, tube sections were removed from more than 20 different locations in the boiler during the 2012 summer shutdown to assess the materials conditions of the boiler. The tubes have been investigated to document wall thickness, fireside corrosion and steamside oxidation rates and morphology and microstructure evolution after 100,000 hours exposure. The mechanical and fracture properties were obtained using small punch test technique (SPT) as well as using miniaturized test specimens. The present paper focuses on investigations and modelling of the influence of sigma phase precipitation on mechanical and thermal stability of the austenitic alloy TP347H that was used as a construction material for superheaters and re-heaters. Obtained results show that even very small amounts of sigma phase affects fracture behaviour significantly. Drop in fracture properties can be clearly identified using miniaturized test specimens or SPT.

Keywords: sigma phase, Tp347HFG stainless steel, miniaturized test specimens, SPT

© 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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