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Abstract
Creep strength of 9 % chromium steels is strongly coupled with the formation and interaction of different precipitate populations like MX (Nb,V)(C,N), M 23 C6 , laves phase and modified Z-phase. Changes in microstructure can be correlated to a change in creep strength. Within this work, a boron-nitrogen balanced 9Cr3W3CoVNb steel is investigated in normalised and tempered (as-received), creep exposed and welded condition. Microstructural haracterisation of normalised and tempered (as-received) and creep exposed samples have been carried out by elemental mapping techniques in transmission electron microscopy (TEM). The creep strength of the base material has been evaluated at 650°C up to a current testing duration of 17.000 hours. First testing results after 10.000 hours show a benefit in strength of the
new grade of about 40 MPa compared to conventional steel grade P92 and 60 MPa to grade P91. The results of the microstructural investigation show only very little changes of the microstructure after 10.000h of creep exposure. The investigations imply a higher microstructural stability of the new steel, compared to other 9% chromium steels.
In welded condition, the steel shows unique formation of its heat-affected zone. Although the steel experiences several phase transformations during the weld thermal cycle, the original base material microstructure is almost maintained in the heat-affected zone. The formation of a homogeneous grain refined region is suppressed and, therefore, less susceptibility to Type IV cracking is expected. Creep tests of crossweld specimens at 650°C and various stress levels are carried out to investigate the susceptibility to Type IV cracking.
new grade of about 40 MPa compared to conventional steel grade P92 and 60 MPa to grade P91. The results of the microstructural investigation show only very little changes of the microstructure after 10.000h of creep exposure. The investigations imply a higher microstructural stability of the new steel, compared to other 9% chromium steels.
In welded condition, the steel shows unique formation of its heat-affected zone. Although the steel experiences several phase transformations during the weld thermal cycle, the original base material microstructure is almost maintained in the heat-affected zone. The formation of a homogeneous grain refined region is suppressed and, therefore, less susceptibility to Type IV cracking is expected. Creep tests of crossweld specimens at 650°C and various stress levels are carried out to investigate the susceptibility to Type IV cracking.
Original language | English |
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Title of host publication | Creep and Fracture in High Temperature Components - Design & Life Assessment Issues |
Place of Publication | Lancaster, Pa |
Publisher | DEStech Publications, Inc |
Pages | 1029-1037 |
ISBN (Print) | 978-1-60595-005-1 |
Publication status | Published - 2009 |
Event | 2009 ECCC International Conference on Creep and Fracture in High Temperature Components: Design & Life Assessment Issues - Zurich, Switzerland Duration: 21 Apr 2009 → 23 Apr 2009 |
Conference
Conference | 2009 ECCC International Conference on Creep and Fracture in High Temperature Components: Design & Life Assessment Issues |
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Abbreviated title | ECCC Creep Conference 2009 |
Country/Territory | Switzerland |
City | Zurich |
Period | 21/04/09 → 23/04/09 |
Treatment code (Nähere Zuordnung)
- Basic - Fundamental (Grundlagenforschung)
Fingerprint
Dive into the research topics of 'Correlation of creep strength and microstructural evolution of a boron alloyed 9Cr3W3CoVNb steel in as-received and welded condition'. Together they form a unique fingerprint.Projects
- 2 Finished
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Materials Development
Dikovits, M. (Co-Investigator (CoI)), Sommitsch, C. (Co-Investigator (CoI)), Caliskanoglu, O. (Co-Investigator (CoI)), Schlacher, C. (Co-Investigator (CoI)), Beal, C. (Co-Investigator (CoI)), Djuric, D. (Co-Investigator (CoI)), Vujic, S. (Co-Investigator (CoI)), Pein, C. (Co-Investigator (CoI)), Krumphals, F. (Co-Investigator (CoI)), Kuduzovic, A. (Co-Investigator (CoI)) & Halici, D. (Co-Investigator (CoI))
1/03/09 → 31/12/24
Project: Research area
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