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Practical Failure Analysis

, Volume 2, Issue 6, pp 50–61 | Cite as

Failure of nickel-aluminum-bronze hydraulic couplings, with comments on general procedures for failure analysis

  • S. P. Lynch
  • D. P. Edwards
  • R. B. Nethercott
  • J. L. Davidson
Peer Reviewed Articles

Abstract

Failures of various types of hydraulic couplings used to connect pipes in a naval vessel are described and used to illustrate some of the general procedures for failure analysis. Cracking of couplings, which were manufactured from nickel-aluminum-bronze extruded bar, occurred in both seawater and air environments. Cracks initiated at an unusually wide variety of sites and propagated in either longitudinal or circumferential directions with respect to the axis of the couplings. Fracture surfaces were intergranular and exhibited little or no sign of corrosion (for couplings cracked in air), and there was very limited plasticity. Macroscopic progression markings were observed on fracture surfaces of several couplings but were not generally evident. At very high magnifications, numerous slip lines, progression markings, and striations were observed. In a few cases, where complete separation had occurred in service, small areas of dimpled overload fracture were observed. It was concluded from these observations, and from comparisons of cracks produced in service with cracks produced by laboratory testing under various conditions, that cracking had occurred by fatigue. The primary cause of failure was probably the unanticipated presence of high-frequency stress cycles with very low amplitudes, possibly due to vibration, resonance, or acoustic waves transmitted through the hydraulic fluid. Secondary causes of failure included the presence of high tensile residual stresses in one type of coupling, undue stress concentrations at some of the crack-initiation sites, and overtorquing of some couplings during installation. Recommendations on ways to prevent further failures based on these causes are discussed.

Keywords

fatigue intergranular cracking nickel-aluminum-bronze progression markings residual stress 

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References

  1. 1.
    D.A. Ryder, T.J. Davies, and I. Brough: “General Practice in Failure Analysis,”Failure Analysis and Prevention, Vol. 11, 9th ed.,ASM Handbook, ASM International, Materials Park, OH, 1986, pp. 15–46.Google Scholar
  2. 2.
    A.J. McEvily:Metal Failures: Mechanisms, Analysis, Prevention, John Wiley, 2002.Google Scholar
  3. 3.
    Anon.: D.G. Ships Procurement Specification 1043, Issue 03, “Nickel-Aluminium Forgings, Forging Stock, Rods and Sections,” MOD, U.K., Ships Dept., March 1981.Google Scholar
  4. 4.
    M. Sadayappan, R. Zavadil, and M. Sahoo: “Effect of Impurity Elements on the Mechanical Properties of Aluminium Bronze Alloy C95800,”Abstracts and Summaries of 8th CF/CRAD Meeting in Naval Applications of Materials Technology, Defence Research Establishment Atlantic, Special Report DREA SR 1999-162, Canada, 1999, pp. 221–34.Google Scholar
  5. 5.
    Anon.: ASTM B 154-89, “Standard Test Method for Mercurous Nitrate Test for Copper and Copper Alloys,” ASTM, Philadelphia, PA.Google Scholar
  6. 6.
    F. Hansan, A. Jahanafrooz, G.W. Lorimer, and N. Ridley: “The Morphology, Crystallography, and Chemistry of Phases in As-Cast Nickel-Aluminium Bronze,”Metall. Trans. A, 1982,13, pp. 1337–45.CrossRefGoogle Scholar
  7. 7.
    A. Jahanafrooz, F. Hasan, G.W. Lorimer, and N. Ridley: “Microstructural Development in Complex Nickel-Aluminium Bronzes,”Metall. Trans. A, 1983,14, pp. 1951–56.CrossRefGoogle Scholar
  8. 8.
    Failure Analysis and Prevention, Vol. 11, 9th ed.,ASM Handbook, ASM International, Materials Park, OH, 1998, p. 26.Google Scholar
  9. 9.
    Fractography, Vol. 12, 10th ed., ASM International, Materials Park, OH, 1999, p. 290.Google Scholar
  10. 10.
    R.N. Parkins, C.M. Rangel, and J. Yu:Metall. Trans. A., 1985,16, p. 1671.Google Scholar
  11. 11.
    E.J. Czyryca and R.B. Niederberger: “Mechanical, Fatigue and Corrosion Properties of Propeller Bronzes,”Propellers ’75, The Soc. of Naval Arch. and Marine Engs., New York, 1976.Google Scholar
  12. 12.
    B.F. Brown: “Stress-Corrosion Cracking Control Measures,”Copper Alloys, National Bureau of Standards, 1977.Google Scholar
  13. 13.
    R.N. Parkins and Y. Suzuki: “Environment-Sensitive Cracking of a Nickel-Aluminium-Bronze Under Monotonic and Cyclic Loading Conditions,”Corros. Sci., 1983,23, pp. 577–99.CrossRefGoogle Scholar
  14. 14.
    R.D. Scheffel, M.A. Phoplonker, J. Byrne, R.L. Jones, and P. Barnes: “Sustained-Load Crack Growth in an Aluminium-Silicon Bronze Alloy,”Fracture Control of Engineering Structures, ECF 6, H.C. Van Elst and A. Bakker, Ed., EMAS, Amsterdam, 1986, pp. 1851–60.Google Scholar
  15. 15.
    J.W.H. Price, R.N. Ibrahim, and D. Ischko: “Sustained-Load Crack Growth Leading to Failure in Aluminium Gas Cylinders in Traffic,”Eng. Fail. Anal., 1997,4, pp. 259–70.CrossRefGoogle Scholar
  16. 16.
    J.J. Lewandowski, V. Kohler, and N.J.H. Holroyd: “Effect of Lead on the Sustained-Load Cracking of Al-Mg-Si Alloys at Ambient Temperatures,”Mater. Sci. Eng., 1987,96, pp.185–95.CrossRefGoogle Scholar
  17. 17.
    J.J. Lewandowski, Y.S. Kim, and N.J.H. Holroyd: “Lead-Induced Solid-Metal Embrittlement of an Excess Silicon Al-Mg-Si Alloy at Temperatures of −4°C to 80°C,”Metall. Trans. A, 1992,23, pp. 1679–89.Google Scholar
  18. 18.
    S.E. Stanzl and H.M. Ebenberger: “Concepts of Fatigue Crack Growth Thresholds Gained by the Ultrasound Method,”Fatigue Crack Growth Threshold Concepts, D.L. Davidson and S. Suresh, Ed., Met. Soc. AIME, 1984, pp. 399–416.Google Scholar
  19. 19.
    M.A. Phoplonker, J. Byrne, T.V. Duggan, R.D. Scheffel, and P. Barnes: “Near-Threshold Fatigue Crack Growth in an Aluminium Bronze Alloy,”Int. Conf. on Fatigue of Engineering Materials and Structures, Vol. 1, Inst. of Mechanical Engineers, London, 1986, pp. 137–44.Google Scholar
  20. 20.
    Metal Fatigue, G. Simes and J.L. Waisman, Ed., McGraw-Hill, London, 1959, p. 11.Google Scholar
  21. 21.
    S. Finnvedan, “Simplified Equations of Motion for the Radial-Axial Vibrations of Fluid-Filled Pipes,”J. Sound Vib., 1997,208, pp. 685–703.CrossRefGoogle Scholar
  22. 22.
    J.K. Smith, P.C. Riccardella, and S.R. Gosselin: “Development of a Screening Procedure for Vibrational Fatigue in Small-Bore Piping,”Int. Pressure Vessels and Piping Codes and Standards, Vol. 2, Current Perspectives, PVP-Vol. 313-2, ASME, 1995, pp. 67–74.Google Scholar
  23. 23.
    F.L. Eisinger: “Designing Piping Systems Against Acoustically Induced Structural Fatigue,”Flow-Induced Vibration, PVP-Vol. 328, ASME, 1996, pp. 397–404.Google Scholar
  24. 24.
    K.J. Miller and W.J. O’Donnell: “The Fatigue Limit and its Elimination,”Fatigue Fract. Eng. Mater. Struct., 1999,22, pp. 545–57.CrossRefGoogle Scholar
  25. 25.
    C. Bathias, L. Drouillac, and P.Le. Francois: “How and Why the Fatigue S-N Curve Does Not Approach a Horizontal Asymptote,”Int. J. Fatigue, 2001,23, pp. S143-S151.CrossRefGoogle Scholar
  26. 26.
    B. Wallen and T. Andersson: “Galvanic Corrosion of Copper Alloys in Contact with Highly Alloyed Stainless Steel in Seawater,” Avesta Corrosion Management, Avesta AB, Avesta Acom No. 2-1987.Google Scholar

Copyright information

© ASM International - The Materials Information Society 2002

Authors and Affiliations

  • S. P. Lynch
    • 1
  • D. P. Edwards
    • 1
  • R. B. Nethercott
    • 1
  • J. L. Davidson
    • 1
  1. 1.Defence Science and Technology OrganizationMelbourneAustralia

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