Modelling and optimizing precipitation in creep resistant austenitic steel 25Cr-20Ni-Nb-N

Vujic Stojan, Beal Coline, Sommitsch Christof, Muhammad Farooq, Sandström Rolf, Zurek Joanna

Research output: Contribution to conferencePaperResearchpeer-review

Abstract

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.

Original languageEnglish
Pages1163-1172
Number of pages10
Publication statusPublished - 1 Jan 2014
Event7th International Conference on Advances in Materials Technology for Fossil Power Plants - Waikoloa, HI, United States
Duration: 22 Oct 201325 Oct 2013

Conference

Conference7th International Conference on Advances in Materials Technology for Fossil Power Plants
CountryUnited States
CityWaikoloa, HI
Period22/10/1325/10/13

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ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology

Cite this

Stojan, V., Coline, B., Christof, S., Farooq, M., Rolf, S., & Joanna, Z. (2014). Modelling and optimizing precipitation in creep resistant austenitic steel 25Cr-20Ni-Nb-N. 1163-1172. Paper presented at 7th International Conference on Advances in Materials Technology for Fossil Power Plants, Waikoloa, HI, United States.