Evaluation of Degradation Causes of the Forged Rotors Made of NiCrMo Steel Grade

Abstract:

Contamination of steel by excessive amount of non metallic inclusions leads tosignificant deterioration of its quality and consequent degradation. Cause of degradation of forgedrotors for steam turbines made of NiCrMoV steel grade is examined in this paper. Metallographicand electron-microscopic analyses were performed, including X-ray microanalysis for detecting thepurity of the forging being examinated. Concurrently, the consequence of failed technologicalproduction process, namely the influence of broken brick for argon blowing at the casting ladle, wasalso examined.

• Periodical: Materials Science Forum (Volume 782)
• Pages: 227-230
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.782.227
• Online since: April 2014
• Authors: Petr Jonšta*, Roman Heide, Irena Vlčková, Miriam Gabčová, Zdenĕk Jonšta, František Jandoš
• Keywords: Degradation, Electron-Microscopic Analysis, Metallographic Analysis, Micro-Purity, Quality of Steel

References

[1] E. Mazancová, Z. Bůžek, K. Mazanec, Evaluation of Influence of Residual Non-Ferrous Metals on Structural Mechanical Properties of Steels (in Czech), Metallurgical Journal 2 (1998) 19-23.

[2] DIN 50 602, Microscopic Testing of Non-Metallic Inclusions in Noble Steels with use of Series of Images, DK 669. 14: 620. 186. 14, German Institute for Normalisation e.V. (1985).

[3] L. Zhang, G. B. Thomas, State of the Art in Evaluation and Control for Steel Cleanliness, ISIJ Int. 43 (2003) 271-291.

DOI: 10.2355/isijinternational.43.271

[4] J. Sojka, Resistance of Steels to Hydrogen Embrittlement (in Czech), first ed., VŠB-TU Ostrava, (2007).