Advertisement

Liquid metal induced embrittlement in fuel line braze joints

  • J. Maciejewski
Peer Reviewed Articles

Abstract

This paper documents an instance of liquid metal induced embrittlement (LMIE) that occurred during the manufacture of automobile engine fuel lines. The fuel lines were constructed of low-carbon steel fittings press fit onto 304 stainless steel tube. The joints were subsequently furnace brazed with copper braze paste. The carbon steel fittings were occasionally observed lying separately as the part exited the brazing furnace. Failure analysis using metallographic techniques, scanning electron microscopy, and energy-dispersive spectroscopy indicated that the fractures were intergranular with no observable ductility. Copper from the braze filler metal was observed on the stainless steel tube fracture surfaces and within the tube wall grain boundaries. Copper and austenitic stainless steel are a well-known LMIE couple. Subsequent investigation indicated the stress required for rapid fracture was due to impacts of the parts against one another and the brazing furnace stationary components while the braze metal was liquid.

Keywords

braze copper liquid metal embrittlement stainless steel 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    R.W. Hertzberg: Deformation and Fracture Mechanics of Engineering Materials, 3rd ed., Wiley Publishing Inc., Indianapolis, IN, 1989.Google Scholar
  2. 2.
    Properties and Selection: Irons, Steels, and High-Performance Alloys, vol. 1, ASM Handbook (formerly Metals Handbook, 10th ed.), ASM International, Materials Park, OH, 1990.Google Scholar
  3. 3.
    Failure Analysis and Prevention, vol. 11, ASM Handbook, ASM International, Materials Park, OH, 2002.Google Scholar
  4. 4.
    Corrosion, vol. 13, ASM Handbook (formerly Metals Handbook, 9th ed.), ASM International, Materials Park, OH, 1987.Google Scholar
  5. 5.
    P.J.L. Fernandes, R.E. Clegg, and D.R.H. Jones: “Failure by Liquid Metal Induced Embrittlement,” Eng. Fail. Anal., 1994, 1(1), pp. 51–63.CrossRefGoogle Scholar
  6. 6.
    C. Heiple, W. Bennett, and T. Rising: “Embrittlement of Several Stainless Steels by Liquid Copper and Liquid Braze Alloys,” Mater. Sci. Eng., 1982, 52, pp. 277–89.CrossRefGoogle Scholar
  7. 7.
    M.G. Nicholas: “A Survey of Literature on Liquid Metal Embrittlement of Metals and Alloys,” Embrittlement by Liquid and Solid Metals, Proc. of Metallurgical Society of AIME, American Institute of Mining, Metallurgical and Petroleum Engineers, Littleton, CO, 1984, pp. 27–39.Google Scholar
  8. 8.
    P. Gordon and H.H. An: “The Mechanisms of Crack Initiation and Crack Propagation in Metal-Induced Embrittlement of Metals,” Metall. Trans. A, 1982, 13, pp. 457–72.CrossRefGoogle Scholar
  9. 9.
    P.J.L. Fernandes and D.R.H. Jones: “Mechanisms of Liquid Metal Induced Embrittlement,” Int. Mater. Rev., 1997, 42(6), pp. 251–61.CrossRefGoogle Scholar
  10. 10.
    C.L. Briant and R.P. Messmer: “Chemical Bonding and Grain Boundary Embrittlement,” Embrittlement by Liquid and Solid Metals, Proc. of the Metallurgical Society of AIME, American Institute of Mining, Metallurgical and Petroleum Engineers, Littleton, CO, 1984, pp. 79–100.Google Scholar
  11. 11.
    D.W. Cameron: “Failures in Large Gas Turbines due to Liquid-Metal Embrittlement,” Mater. Char., 1994, 33, pp. 37–43.CrossRefGoogle Scholar
  12. 12.
    Brazing Manual, 3rd ed., American Welding Society, Miami, FL, 1976.Google Scholar
  13. 13.
    ASME Boiler and Pressure Vessel Code, vol. II-C, SFA-5.8, Appendix, American Society of Mechanical Engineers, New York, NY.Google Scholar
  14. 14.
    The Brazing Book, Handy & Harman, Rye, NY, 1983.Google Scholar
  15. 15.
    E. F. Nippes and D.J. Ball: “Copper-Contamination Cracking: Cracking Mechanism and Crack Inhibitors,” Weld. J., 1982, 61(3), pp. 76s-81s.Google Scholar
  16. 16.
    R.K. Holbert, A.G. Dobbins, and R.K. Bennett: “Copper Contamination Cracking in Thin Stainless Steel Sheet,” Weld. J., 1987, 66(8).Google Scholar

Copyright information

© ASM International 2005

Authors and Affiliations

  • J. Maciejewski
    • 1
  1. 1.Applied Technical ServicesMarietta

Personalised recommendations