Journal of Failure Analysis and Prevention

, Volume 19, Issue 4, pp 890–902 | Cite as

Failure of Locking Wires of an Aeroengine Component: Attributed Primarily to Over-twisting and Secondarily to Engine Vibration and Improper Material Selection

  • Mrityunjoy HazraEmail author
  • Jalaj Kumar
  • Satyapal Singh
Case History---Peer-Reviewed


Each of failed, working and unused (as-fabricated) locking wires used in fastening engine exhaust pipe of an aeroengine was analyzed during the course of failure investigation. Relevant background information is as follows: (1) Specification GOST 18143-72 was followed in manufacturing those wires, and (2) wires were for one-time use only. The failed and all other wire types were found to be made of as-specified AISI 321 austenitic stainless steel, based on compositional and microstructural analyses with high volume fraction of phases of Ti–C–N family. High volume fraction of Ti–C–N phases led to unacceptably higher strengths in each of the failed as well as non-failed wires (UTS value in excess of 580 MPa), while the as-specified material is supposed to have breakage strength of 520 MPa. The principle contributing factor to failure of one wire of the locking wire pair is over-twisting of the wire during fixing it to the main assembly. Effect of engine vibration in form of vibration fatigue was found to be of secondary in nature and did not cause the failure directly. It assisted in the final (propagation) stage of failure. Other wire failed by overload as a result of over-twisting of its counterpart. Temperature did not play any role in the present failure. Failure mechanism was verified by simulated experimental results on fractographs conducted with the unused wire and obtained by twisting, untwisting and retwisting. Excessively high and unspecified strength of the material and lower toughness (as manifested by Ti–C–N particles–matrix interfacial cracking) might have contributed to the present failure in a secondary way.


Locking wire AISI 321 austenitic stainless steel Ti–C–N phases Twisting Temperature Vibration fatigue Rubbing 



The authors would like to thank Dr. Vikas Kumar, Distinguished Scientist (DS) and the Director, DMRL, for his constant encouragement to work on the present field. Also, funding from DRDO is gratefully acknowledged.


  1. 1.
    Technical Note on Safety Lockwire Practices For Engines Produced in Accordance with ASTM F2339, issued on 09-09-2010 by ECi Ltd, Accessed 20 Oct 2018Google Scholar
  2. 2.
  3. 3.
  4. 4.
    ASTM A580/A580M – 12a, Standard specification for stainless steel wireGoogle Scholar
  5. 5.
    ASTM A555/A555M – 05, Standard specification for general requirements for stainless steel wire and wire rods (Reapproved 2009)Google Scholar
  6. 6.
  7. 7.
    A.M. Abd El-Rahman, An investigation on the microstructure, tribological and corrosion performance of AISI 321 stainless steel carbonitrided by RF plasma process. Surf. Coat. Technol. 205(2), 674–681 (2010)CrossRefGoogle Scholar
  8. 8.
    D. Tabor, The hardness and strength of metals. J. Inst. Met. 79, 1–18 (1951)Google Scholar
  9. 9.
    M.C. Shaw, G.J. DeSalvo, A new approach to plasticity and its application to blunt two dimensional indenters. Trans. ASME J. Eng. Ind. 92, 469–479 (1970)CrossRefGoogle Scholar
  10. 10.
    M.C. Shaw, G.J. DeSalvo, The role of elasticity in hardness testing. Met. Eng. Q. 12, 1–7 (1972)Google Scholar
  11. 11.
    J.H. Westbrook, H. Conrad (eds.), The Science of Hardness Testing (American Society for Metals, Metals Park, 1973), pp. 75–79Google Scholar
  12. 12.
  13. 13.
    T. Sourmail, Precipitation in creep resistant austenitic stainless steels. Mater. Sci. Technol. 17(1), 1–14 (2001)CrossRefGoogle Scholar
  14. 14.
    J. Choi, B. Seong, S.C. Baik, H. Lee, Precipitation and recrystallization behavior in extra low carbon steels. ISIJ Int. 42(8), 889–893 (2002)CrossRefGoogle Scholar
  15. 15.
    G.E. Totten, Steel Heat Treatment Metallurgy and Technologies, 2nd edn. (Taylor & Francis Group, Abington, 2007)Google Scholar
  16. 16.
    P. Podaný, P. Martínek, P. Nacházel, M. Balcar. Heat treatment of reactor vessel steel AISI 321, in Recent trends in structural materials, COMAT 2012, Plzeň, Czech Republic, 21–22 Nov 2012Google Scholar
  17. 17.
    M Farooq, Strengthening and degradation mechanisms in austenitic stainless steels at elevated temperatures, Ph.D. Thesis, Royal Institute of Technology (KTH), Stockholm, Sweden, 2013Google Scholar
  18. 18.
    R. A. Abrahams, The development of high strength corrosion resistant precipitation hardening cast steels, Ph.D. Thesis, Pennsylvania State University, 2010Google Scholar
  19. 19.
    A Gharehbaghi, Precipitation study in a high temperature austenitic stainless steel using low voltage energy dispersive x-ray spectroscopy, Master’s Thesis, Royal Institute of Technology (KTH), Stockholm, Sweden, 2012Google Scholar
  20. 20. Accessed 14 Dec 2018
  21. 21.
    ASM International, Austenitic Stainless Steel in Stainless Steels for Design Engineers (ASM International, Materials Park, OH, 2008)Google Scholar
  22. 22.
    A.I. Gusev, Nitrogen partial pressure of stoichiometric and nonstoichiometric titanium, vanadium and niobium nitrides and carbonitrides. Phys. Stat. Sol. (b) 209, 267 (1998)CrossRefGoogle Scholar
  23. 23.
    R.M. Shemenski, Fractography of steel drive cables. Met. Eng. Q. 14(2), 398–402 (1974)Google Scholar
  24. 24.
    F.P. Beer, E.R. Johnston Jr., J.T. Dewolf (eds.), Mechanics of Materials, 3rd edn. (The Mcgraw-Hill, New York, 2002)Google Scholar
  25. 25.
    J.M. Gere (ed.), Mechanics of Materials, 6th edn. (Thomson Learning Inc., Belmont, 2004)Google Scholar
  26. 26.
    W.K. Honeycombe, H.K.D.H. Bhadeshia, Steels: Microstructure and Properties, 3rd edn. (Elsevier, Amsterdam, 2006), p. 267Google Scholar
  27. 27.
    Chapter 7. Aircraft hardware, control cables, and turnbuckles, ac 43.13-1b, 9-8-98,…/chapter_07.pdf. Accessed 20 Oct 2018
  28. 28.
    ECi technical note, Accessed 20 Oct 2018
  29. 29.
    H. Halfa, Recent trends in producing ultrafine grained steels. J. Miner. Mater. Charact. Eng. 2, 428–469 (2014). Google Scholar
  30. 30.
    R.C.K. Nkhoma, Hot Working Characteristics of AISI 321 in Comparison to AISI 304 Austenitic Stainless Steels, Ph.D. Thesis. (University of Pretoria, Republic of South Africa, 2014)Google Scholar
  31. 31.
    A. Mironenko, Nondestructive inspection of steel wire ropes, in Proceedings of MICNDT 2011 Google Scholar
  32. 32.
    South African Standard, Condition Assessment of Steel Wire Ropes on Mine Winders (South African Standard, Pretoria, 1996)Google Scholar
  33. 33.
    ISO 4309-2010, Cranes—Wire ropes—Care and maintenance, inspection and discardGoogle Scholar

Copyright information

© ASM International 2019

Authors and Affiliations

  1. 1.Defence Metallurgical Research Laboratory (DMRL)HyderabadIndia

Personalised recommendations