Ermittlung der Zähigkeitsentwicklung großer Schmiedestücke während der Wärmebehandlung

Translated title of the contribution: Evaluation of the development of the toughness behaviour for large forgings during the heat treatment

Gerhard Panzl

Research output: ThesisMaster's Thesis

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Abstract

Large Forgings for thermal power plants are heat treated to achieve proper material properties for failure-free service. Caused by the large dimensions, the local cooling conditions vary in the cross sections from the center to the rim position. In this work, two typical materials were considered and Charpy toughness as well as three-point-bending samples were thermally simulated according to the real forging conditions. According to the complete quenching and tempering cycle, all samples were tested after quenching. The measured toughness values (Av) and J-integral values (Juc bzw. J0,2BL) are evaluated across the cross section. It is shown, that the toughness behaviour of the 3-3,5 % NiCrMoV steel follows the expectation, that the bainitic microstructure is much tougher at slow cooling conditions. However, the results for the 9 – 12 % Cr steel show a different behaviour, which depends also from the cooling conditions. Depending on the actual position in the cross section, there is some reheating or tempering of the martensitic structure, which affects the toughness behaviour. A more detailed investigation was done per hardness measurement, and determination of residual austenite fraction and carbide content, as well as SEM analysis of the fracture surface.
Translated title of the contributionEvaluation of the development of the toughness behaviour for large forgings during the heat treatment
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Buchmayr, Bruno, Supervisor (internal)
Award date4 Apr 2014
Publication statusPublished - 2014

Bibliographical note

embargoed until 04-03-2019

Keywords

  • large forgings
  • toughness behaviour
  • charpy impact energy
  • J-integral

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