Modelling and optimizing precipitation in creep resistant austenitic steel 25Cr-20Ni-Nb-N
2014 (English)In: Advances in Materials Technology for Fossil Power Plants - Proceedings from the 7th International Conference, 2014, 1163-1172 p.Conference paper (Refereed)
25Cr-20Ni-Nb-N (Tp310HCbN) steel is a promising austenitic steel for applications in superheater tubes in coal fired thermal power plants due to the high creep strength and oxidation resistance. In this work, the microstructural evolution of this material during heat treatment and thermal ageing has been investigated. The investigations were carried out by Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). Besides, equilibrium and Scheil calculations were carried out using the thermodynamic software MatCalc to analyse the stable phases and the solidification process, respectively. Precipitation calculations during solution annealing and subsequent ageing at 650 and 750°C were performed to predict the phase fraction and precipitates radius up to 10.000h ageing time. SEM and TEM investigations of aged specimens revealed the presence of six different precipitates: M23C 6, Cr2N, sigma, Z-phase, eta-phase (Cr3Ni 2Si(C,N)) and Nb(C,N). These precipitates were predicted and confirmed by MatCalc simulations. The calculated phase fraction and mean radius show good agreement with experimental data. Finally, simulations of different Cr-, C- and N-content in Tp310HCbN were performed.
Place, publisher, year, edition, pages
2014. 1163-1172 p.
Austenitic steel, Energy dispersive spectroscopy, Fossil fuel power plants, Scanning electron microscopy, Thermoelectric power plants, Transmission electron microscopy, Coal fired thermal power plants, Creep resistant, Creep strengths, Energy dispersive spectroscopies (EDS), Light optical microscopies, Scheil calculations, Solidification process, Solution annealing, Nickel
IdentifiersURN: urn:nbn:se:kth:diva-168373ScopusID: 2-s2.0-84900433205OAI: oai:DiVA.org:kth-168373DiVA: diva2:815882
7th International Conference on Advances in Materials Technology for Fossil Power Plants; Waikoloa, HI; United States
QC 201506022015-06-022015-06-022015-06-02Bibliographically approved