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Influence of alloying, stress concentration, and surface hardening on the fatigue resistance of rotor steel

  • Strength Properties
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Metal Science and Heat Treatment Aims and scope

Conclusions

  1. 1.

    In alloying of 0.11–0.17% C steel used for the production of turbogenerator rotors with nickel up to 4.5–4.7% in comparison with type 25KhN3MFA steels used at present for this purpose a fine grain and a uniform bainitic structure are obtained in a broad range of cooling rates from the austenitizing temperature and also a high guaranteed level of mechanical properties of σ0.2 ≧ 600 N/mm2, σt ≧ 800 N/mm2, δ ≧ 18%, ψ ≧ 50%, a0.25≧100 J/cm2, and T50=−60°C.

  2. 2.

    The steel with 0.11–0.17% C and 4.2–4.6% Ni (heat 1) has a higher fatigue limit for unnotched specimens (350–380 N/mm2) in comparison with steel I of type 25KhN3MFA (300–320 N/mm2).

    Surface plastic deformation of specimens with a groove leads to an increase in the fatigue limit from 360 to 410 N/mm2, which makes it possible to recommend this method for the purpose of an additional increase in the fatigue resistance of turbogenerator rotors.

  3. 3.

    Combined alloying with niobium and cobalt of steel with a reduced carbon content and an increased nickel content (heat 3) causes an increase in the fatigue limit of unnotched specimens from 350 to 360 N/mm2 and of specimens with a stress raiser from 200 to 220 N/mm2.

  4. 4.

    The use in melting of the steels of pure primary charge materials makes it possible to obtain the very highest fatigue limit on unnotched specimens (σ−1 = 400 N/mm2) and specimens with a groove (σ=1r = 250 N/mm2).

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Authors
  1. N. E. Naumchenkov
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  2. O. V. Filimonova
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  3. I. A. Borisov
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Additional information

Central Scientific-Research Institute for Machine Building Technology Scientific and Production Union. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 15–19, September, 1986.

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Naumchenkov, N.E., Filimonova, O.V. & Borisov, I.A. Influence of alloying, stress concentration, and surface hardening on the fatigue resistance of rotor steel. Met Sci Heat Treat 28, 637–642 (1986). https://doi.org/10.1007/BF00742741

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  • DOI: https://doi.org/10.1007/BF00742741

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