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@PHDTHESIS{Talik:825997,
      author       = {Talik, Michal},
      title        = {{I}nfluence of {I}nitial {T}hermomechanical {T}reatment on
                      {H}igh {T}emperature {P}roperties of {L}aves {P}hase
                      {S}trengthened {F}erritic {S}teels},
      volume       = {338},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-00269},
      isbn         = {978-3-95806-175-0},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {xxiii, 130 S.},
      year         = {2016},
      note         = {RWTH Aachen, Diss., 2016},
      abstract     = {The aim of this work was to design 17 $wt\%Cr$ Laves phase
                      strengthened HiperFer ($\textbf{Hi}$gh
                      $\textbf{per}$fomrance $\textbf{Fer}$rite) steels and
                      evaluate their properties. This class of steel is supposed
                      to be used in Advanced Ultra Super Critical power plants.
                      Such cycles exhibit higher efficiency and are
                      environmentally friendly, but improved materials with high
                      resistance to fireside/steam oxidation and suficient creep
                      strength are required. The work focused on the
                      characterization of creep properties of 17Cr2.5W0.5Nb0.25Si
                      heat resistant steel. Small batches of steels with nominal
                      compositions of 17Cr3W0.5Nb0.25Si and 17Cr3W0.9Nb0.25Si were
                      used to analyze the inuence of chemical composition on the
                      precipitation behaviour in comparison to 17Cr2.5W0.5Nb0.25Si
                      steel. Creep strength of HiperFer steels is ensured by fine
                      dispersion of thermodynamically stable Laves phase
                      particles, while maintaining high corrosion resistance by a
                      relatively high chromium content. Design of HiperFer steels
                      was accomplished by thermodynamic modeling (Thermocalc) with
                      the main tasks of elimination of the unwelcome brittle
                      (Fe,Cr)-$\sigma$ phase and maximization of the content of
                      the strengthening C14 Fe$_{2}$Nb type Laves phase particles.
                      Long term annealing experiments of all HiperFer steels were
                      performed at 650 °C in order to evaluate the role of
                      chemical composition and initial thermo-mechanical treatment
                      state on precipitation behaviour. Laves phase particles
                      formed quickly after few hours and the size of precipitates
                      did not change signicantly within 1,000 hours. The observed
                      development of Laves phase particles was compared with
                      thermodynamical calculations (TC-Prisma). The creep
                      properties of 17Cr2.5W0.5Nb0.25Si steel in different initial
                      thermo-mechanical treatment states were tested at 650 °C.
                      The influence of different cold rolling procedures, and heat
                      treatments was investigated. Increased cold rolling
                      deformation had a positive effect resulting not only from
                      work hardening, but from the acceleration of Laves phase
                      particle precipitation. The recrystallization annealed
                      material exhibited signficantly shorter creep life in
                      comparis onto the rolled material. Two promising heat
                      treatments restoring the creep strength up to the level of
                      rolled material were identified. Tempering at 540 °C
                      accelerates the formation and reduces the size of
                      strengthening Laves phase precipitates. Short term tempering
                      at 800 °C causes dense precipitation of Laves phase
                      particles at grain boundaries without detrimental influence
                      on the morphology of Laves phase particles in the grain
                      interiors. Dense precipitation of coarse Laves phase
                      particles causes a retardation of grain boundary sliding in
                      the later periods of creep exposure.},
      cin          = {IEK-2},
      cid          = {I:(DE-Juel1)IEK-2-20101013},
      pnm          = {899 - ohne Topic (POF3-899) / HITEC - Helmholtz
                      Interdisciplinary Doctoral Training in Energy and Climate
                      Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-899 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/825997},
}