CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

UNDERSTANDING OF 9-12% CR STEELS ON A NANO- AND SUBNANO-SCALE - THE SECRET OF TAF

Fang Liu (Institutionen för teknisk fysik, Mikroskopi och mikroanalys) ; Hans-Olof Andrén (Institutionen för teknisk fysik, Mikroskopi och mikroanalys)
2nd International conference of Super high strength steels p. paper 81. (2010)
[Konferensbidrag, övrigt]

The old Japanese high-boron 10.5% Cr martensitic test steel TAF, has still unsurpassed long-term creep strength at high temperatures amongst 9-12% chromium steels. Within the framework of the European COST 501 project, a series of very similar test materials were produced, and one of these has now been investigated by atom probe tomography. It contains 300 ppm B and was studied in the as-tempered condition. In-situ lift out technique was employed to pinpoint M23C6 precipitates located in vicinity and away from the prior austenite grain boundaries (PAGB). It was found that the B concentration is as high as 2 at.% in a M23C6 precipitate located in vicinity of a PAGB. In addition the concentration increases towards the centre of the precipitate. For M23C6 located more than10 micrometers away from the PAGB the B concentration is less than 1 at.%. The concentration is usually slightly higher towards the interface of M23C6/matrix. This phenomenon is discussed in the light of the B diffusion process. Disk-like small, ~ 10 nm, MX precipitates with a very high number density were observed. Some of the precipitates, which contain relatively high C, contain high amount of Nb as well. Trace of B was found in many of these precipitates. The secret of TAF appears to be two unusually dense precipitate families, both stabilized by boron.

Nyckelord: 9-12% Cr steels, creep, boron, atom probe tomography



Den här publikationen ingår i följande styrkeområden:

Läs mer om Chalmers styrkeområden  

Denna post skapades 2010-12-23. Senast ändrad 2015-03-30.
CPL Pubid: 131756

 

Institutioner (Chalmers)

Institutionen för teknisk fysik, Mikroskopi och mikroanalys (2005-2012)

Ämnesområden

Energi
Materialvetenskap
Hållbar utveckling
Övrig teknisk materialvetenskap

Chalmers infrastruktur