Fracture Toughness of Large Forgings for Power Producing Industry

Abstract:

The steam turbine rotors represent large components both in radial and axial directions. Their local properties generally differ from one forging to another, or if we compare head and bottom parts of the original ingot, or central and circumferential localities of one rotor body respectively, or if we compare the properties of separate discs e.g. in the case of welded rotors. These differences stem from both even slight changes in the chemical composition (of separate heats or even within one ingot) and thermo-mechanical treatment and in the differences in technology with respect to the real shape and size of the forgings in question. In the paper, the consequences of the differences in fracture toughness characteristics in various rotor localities are discussed with respect to the rotors operational safety taking into account the existence of cracks and material degradation.

• Periodical: Key Engineering Materials (Volumes 577-578)
• Pages: 593-596
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.577-578.593
• Online since: September 2013
• Authors: Václav Mentl
• Keywords: Fracture Mechanics, Large Forgings, Steam Turbine Rotor Steels

References

[1] Janda R., Mentl V.: Mesung der Bruchzaehigkeit an grossen Probenkoerpern, Sb.konf. "Verformung und Bruch", Magdeburg, 1985.

[2] Janda R., Mentl V.: Der Einfluss der Probendicke auf bruchmechanische Kennwerte, VIII. Symp. "Verformung und Bruch", Magdeburg, 1988.

[3] Janda R., Mentl V., Sulek M.: Bewertung der Staehle fuer extrem beanspruchte Rotore von Dampfturbinen mit Hilfe der Bruchmechanik-Verfahrten, Neue Hutte 36 (1991), No.10.

[4] Mentl V.: Mapping of fracture toughness values in large forgings, Proc. 18th European Conf.on Fracture "Fracture of Materials and Structures from Micro to Macro Scale", DVM Deutscher Verband fuer Materialforschung und Pruefung e.V. Dresden, Germany, August30-Sept.3, 2010, paper No.137, ISBN 978-3-00-031802-3.