Practical Failure Analysis

, Volume 3, Issue 3, pp 89–97 | Cite as

Metallurgical investigation of a prematurely failed roller bearing used in the support and tilting system of a steel making converter used in an integrated steel plant

  • Amitava Ray
  • S. K. Dhua
  • K. B. Mishra
  • S. Jha
Peer Rerieved Articles
  • 156 Downloads

Abstract

An extensive metallurgical investigation was carried out on samples of a failed roller bearing from the support and tilting system of a basic oxygen furnace (BOF) converter used in the steel melting shop of an integrated steel plant. The converter bearing was fabricated from low-carbon, carburizing grade steel and had failed in service within a year of fitting to a repaired shaft. Microscopic observations of both the broken roller and inner-race samples revealed subsurface cracking and preponderance of brittle oxide and other macroinclusions. Electron probe microanalysis (EPMA) studies confirmed that the brittle oxides that formed stringers were alumina, and the other macroinclusions were complex silicates. Both the alumina and silicate inclusions were deleterious to contact-fatigue properties. Microstructurally, the carburized regions of the broken roller and of inner-race samples contained high-carbon tempered martensite. Microhardness measurements revealed that although the core hardness of the roller and the inner-race samples were similar, the surface hardness of the roller was approximately 8.5 HRC units harder than that of the inner-race. Scanning electron microscope (SEM) observations of the roller fracture surface revealed striations indicative of fatigue, and energy-dispersive spectrometric (EDS) analyses corroborated a high incidence of silicate inclusions at crack sites. The study suggests that the failure of the bearing occurred because the hardness difference between the roller bearing and the inner-race surfaces resulted in wear of the inner-race. The wear led to shaft misalignment and play during service. The misalignment, coupled with the presence of inclusions, caused fatigue failure of the roller bearing.

Keywords

bearing failure fatigue nonmetallic inclusions rolling-element bearing tempered martensite 

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References

  1. 1.
    C.A. Moyer: “Friction and Wear of Bearing Steels,”Friction, Lubrication and Wear Technology, vol. 18,ASM Handbook, T.B. Zorc, Ed., ASM International, 1992, pp. 725–733.Google Scholar
  2. 2.
    H. Burrier: “Bearing Steels,”Properties and Selection: Irons, Steels, and High-Performance Alloys, vol. 1,ASM Handbook, 10th ed., S.R. Lampman and T.B. Zorc, Ed., ASM International, 1990, pp. 380–388.Google Scholar
  3. 3.
    F.R. Hutchings: “A Survey of the Causes of Failure of Rolling Bearings,”Failure Analysis: The British Engine Technical Reports, P.M. Unterweiser, Ed., American Society for Metals, Metals Park, OH, 1981, pp. 450–471.Google Scholar
  4. 4.
    E.V. Zaretsky, R.J. Parker, and W.J. Andersen: “Component Hardness and their Effect on Bearing Fatigue,”J. Lubr. Technol. — T. ASME, Jan 1967, p. 47.Google Scholar
  5. 5.
    R.L. Widner: “Failure of Rolling-Element Bearing,”Failure Analysis and Prevention, vol. 11,ASM Handbook, American Society for Metals, Metals Park, Ohio, 1986, pp. 490–513.Google Scholar
  6. 6.
    A. Ray, S.K. Dhua, and S. Jha: “Electron Probe Microanalysis: Some Applications in the Assessment of Steel Product Quality,”X-ray Spectrom., 1999,28(1), pp. 41–51.CrossRefGoogle Scholar
  7. 7.
    D. Brookesbank and K.W. Andrews: “Steels Fields around Inclusions and their Relation to Mechanical Properties,”J. Iron Steel I., 1972,210(4), pp. 246–255.Google Scholar

Copyright information

© ASM International - The Materials Information Society 2003

Authors and Affiliations

  • Amitava Ray
    • 1
  • S. K. Dhua
    • 1
  • K. B. Mishra
    • 1
  • S. Jha
    • 1
  1. 1.Physical Metallurgy GroupResearch & Development Centre for Iron & Steel, Steel Authority of India LimitedRanchiIndia

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