Metallurgical Investigations of Microstructure and Behaviour of High-Alloyed Manganese-Chromium Austenitic Steels for Generator-Rotor Retaining Rings
The exciter coil of large generator rotors opens up into the so-called coil head at the body ends. The coil, here, must be secured by retaining rings against relative movements resulting from electro-magnetic forces but especially against centrifugal force. Because of their structural function, these retaining rings must have very high strength values — yield point up to max. 1300 N/mm2 — and consist of a non-magnetic material. Several extensive reports have been made recently about the demands on generator retaining rings and the properties of materials employed as well as cases of damages1–3. The austenitic steel X 55 MnCr(N)18K (comp. Table 1) with a nitrogen content of 0.10 %, as examined here, is mainly employed throughout the world. Nitrogen improves the strength and simultaneously stabilizes the austenite.
KeywordsEutectoid Transformation Transformation Diagram Electron Diffraction Experiment Metallurgical Investigation Great Magnification
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- 1.E. Heinrich, G. Kröncke, and G. Tacke, Stahl u. Eisen 102, 1183 (1982).Google Scholar
- 2.M.O. Speidel, VGB-Kraftwerktechnik 62, 424 (1982).Google Scholar
- 3.J. Ewald, H. Hübner, H. Kraemer, and A.W. Schmitz, Sammelband VGB-Konferenz: Werkstoffe u. Schweißtechnik im Kraftwerk 1980, p. 280.Google Scholar
- 4.J. Albrecht and B. Scarlin, BBC-Forschungsbericht KLR 82-118 C.Google Scholar
- 5.M. Kroneis and R. Gattringer, Stahl u. Eisen 81, 431 (1961).Google Scholar