Advertisement

Welding in the World

, Volume 62, Issue 4, pp 783–792 | Cite as

Exacerbated stress corrosion cracking in arc welds of 7xxx aluminum alloys

Henry Granjon prize 2017 winner Category B: Materials Behaviour and Weldability
Research Paper
  • 80 Downloads

Abstract

Cu-lean, high-strength 7xxx series aluminum alloys (AAs) are increasingly utilized in welded structures for vehicle light-weighting. The complex stress corrosion cracking (SCC) phenomenon in the 7xxx AA base metals has been extensively studied in the literature. However, the SCC in a welded joint is further compounded by the existence of highly inhomogeneous microstructure formed during welding. The present investigation is focused on the exacerbated SCC observed in the joints made of AA 7003-T4 (Al–Zn–Mg) plates welded with AA 5356 (Al–Mg) filler metal. It studies the contribution to SCC by a variety of factors especially the precipitates in the weld toe and the heat-affected zone in the as-welded and post-weld heat-treated conditions. The stress intensity factor experienced at the crack tip is ranked using the peak strain measured using the digital image correlation technique. Based on the testing results, a theory for the exacerbated SCC in the weld joints is established. Finally, the feasibility of two different engineering solutions to SCC in these weldments is discussed.

Keywords

Aluminum alloys Arc welding Stress corrosion cracking Fused-overlap zone Transmission electron microscopy 

Abbreviations

AA

Aluminum alloy

AW

As-welded

BM

Base metal

DIC

Digital image correlation

EDM

Electron discharge machining

EDS

Energy-dispersive x-ray spectroscopy

FM

Filler metal

FOZ

Fused-overlap zone

FL

Fusion line

FSW

Friction stir welding

FZ

Fusion zone

HAZ

Heat-affected zone

IGC

Intergranular corrosion

KI

Stress intensity

KISCC

Critical SCC stress intensity

PB

Paint bake

PBTC

Paint bake thermal cycle

SCC

Stress corrosion cracking

SCC

Stress corrosion cracking

TMAZ

Thermo-mechanically affected zone

WT

Weld toe

Notes

Acknowledgements

The present research was supported by Honda R&D Americas, Inc. through the Manufacturing and Materials Joining Innovation Center (Ma2JIC), a NSF industry/university cooperative research center (I/UCRC). STEM was performed by Rachel Seibert of the Illinois Institute of Technology using the FEI Talos F200X STEM provided by the Department of Energy, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. Helpful discussion with Dr. Niyanth Sridharan of Oak Ridge National Laboratory (ORNL) is acknowledged.

References

  1. 1.
    Knight S, Pohl K, Holroyd N, Birbilis P, Muddle B, Goswami RLS (2015) Some effects of alloy composition on stress corrosion cracking in Al–Zn–Mg–Cu alloys. Corros Sci 98:50–62.  https://doi.org/10.1016/j.corsci.2015.05.016 CrossRefGoogle Scholar
  2. 2.
    Lin J-C, Liao H-L, Jehng W-D, Chang C-H, Lee S-L (2006) Effect of heat treatments on the tensile strength and SCC-resistance of AA7050 in an alkaline saline solution. Corros Sci 48(10):3139–3156.  https://doi.org/10.1016/j.corsci.2005.11.009 CrossRefGoogle Scholar
  3. 3.
    Sun X, Zhang B, Lin H, Zhou Y, Sun L, Wang J, Han E-H, Ke W (2013) Correlations between stress corrosion cracking susceptibility and grain boundary microstructures for an Al–Zn–Mg alloy. Corros Sci 77:103–112.  https://doi.org/10.1016/j.corsci.2013.07.032 CrossRefGoogle Scholar
  4. 4.
    Hatamleh O, Singh P, Garmestani H (2009) Corrosion susceptibility of peened friction stir welded 7075 aluminum alloy joints. Corros Sci 51(1):135–143.  https://doi.org/10.1016/j.corsci.2008.09.031 CrossRefGoogle Scholar
  5. 5.
    Mousavi M, Cross C, Grong O, Hval M (1997) Controlling weld metal dilution for optimised weld performance in aluminium. Sci Technol Weld Join 2(6):275–278.  https://doi.org/10.1179/stw.1997.2.6.275 CrossRefGoogle Scholar
  6. 6.
    S. Yang and Q. Lin, Adv. Mater. Res., Vols. 148–149, pp. 640–643, 2011Google Scholar
  7. 7.
    Kou S (2003) Welding metallurgy, 2nd edn. Wiley, New YorkGoogle Scholar
  8. 8.
    Liao C (1993) SCC behavior of an Al–3.7wt%Zn–2.5wt%Mg alloy before and after welding in 3.5% NaCl Solution. Corrosion 49(1):52–59.  https://doi.org/10.5006/1.3316034 CrossRefGoogle Scholar
  9. 9.
    Borchers T, McAllister D, Zhang W (2015) Metall. Mater Trans A 46A:1827–1823CrossRefGoogle Scholar
  10. 10.
    Borchers T, Seid A, Babu S, Shafer P, Zhang W (2015) Effect of filler metal and post-weld friction stir processing on stress corrosion cracking susceptibility of Al–Zn–Mg arc welds. Sci Technol Weld Join 20(6):460–467.  https://doi.org/10.1179/1362171814Y.0000000273 CrossRefGoogle Scholar
  11. 11.
    M. Reboul, B. Dubost and M. Lashermes, Corros Sci, vol. 25, pp. 999–1018, 1983Google Scholar
  12. 12.
    Jha AK, Shiresha GN, Sreekumar K (2008) Stress corrosion cracking in alumnium alloy AFNOR 7020-T6 water tank adaptor for liquid propulsion system. Eng Fail Anal 15(6):787–795.  https://doi.org/10.1016/j.engfailanal.2007.05.009 CrossRefGoogle Scholar
  13. 13.
    Frankel G, Xia Z (1999) Localized corrosion and stress corrosion cracking resistance of friction stir welded aluminum alloy 5454. Corrosion 55(2):139–150.  https://doi.org/10.5006/1.3283974 CrossRefGoogle Scholar
  14. 14.
    M. Speidel, Met. Trans, vol. 6A, p. 1975Google Scholar
  15. 15.
    Holroyd N, Vasudevan A, Christodoulou L (1989) Stress corrosion of high-strength aluminum alloys. Treatise Mater Sci Technol 31:463–483.  https://doi.org/10.1016/B978-0-12-341831-9.50021-8 CrossRefGoogle Scholar
  16. 16.
    Baumgartner M, Kaesche H (1988) Intercrystalline corrosion and stress corrosion cracking of AlZnMg alloys. Corrosion 44(4):231–239.  https://doi.org/10.5006/1.3583931 CrossRefGoogle Scholar
  17. 17.
    Sprowls D, Brown R (1969) Fundamental aspects of stress corrosion cracking, R. Staehle, Ed. Houston, National Association of Corrosion EngineersGoogle Scholar
  18. 18.
    R. Braun, Mat.-wiss. u. Werkstofftech, vol. 38, no. 9, pp. 674–688, 2007Google Scholar
  19. 19.
    Burleigh T (1991) The postulated mechanisms for stress corrosion cracking of aluminum alloys: a review of the literature 1980–1989. Corrosion 47(2):89–97.  https://doi.org/10.5006/1.3585235 CrossRefGoogle Scholar
  20. 20.
    G. Lu and e. al., Hydrogen enhanced local plasticity in aluminum: an ab initio study, 2002Google Scholar
  21. 21.
    S. Lynch, Acta Metall., vol. 36, p. 2639, 1988Google Scholar
  22. 22.
    Najjar D, Magnin T, Warner T (1997) Influence of critical surface defects and localized competition between anodic dissolution and hydrogen effects during stress corrosion cracking of a 7050 aluminium alloy. Mater Sci Eng A 238(2):293–302.  https://doi.org/10.1016/S0921-5093(97)00369-9 CrossRefGoogle Scholar
  23. 23.
    Frankel G (1998) Pitting corrosion of metals. J Electrochem Soc 145(6):2186–2198.  https://doi.org/10.1149/1.1838615 CrossRefGoogle Scholar
  24. 24.
    Zaid B, Saidi D, Benzaid A, Hadji S (2008) Corros. Sci 50:1841–1847Google Scholar
  25. 25.
    Nicolas M, Deschamps A (2003) Characterisation and modelling of precipitate evolution in an Al–Zn–Mg alloy during non-isothermal heat treatments. Acta Mater 51(20):6077–6094.  https://doi.org/10.1016/S1359-6454(03)00429-4 CrossRefGoogle Scholar
  26. 26.
    Muller I, Galvele J (1976) Corros Sci 17:995–1007CrossRefGoogle Scholar
  27. 27.
    J. Dabrowski and J. Kish, Corros., vol. 71, pp. 895–907, 2015Google Scholar
  28. 28.
    Deng Y, Peng B, Xu G, Pan Q, Ye R, Wang Y, Lu L and Z. Yin, Corros Sci, vol. 100, pp. 57–72, 2015, DOI:  https://doi.org/10.1016/j.corsci.2015.06.031
  29. 29.
    Nicolas M, Deschamps A (2004) Metall Mater Trans A 35A:1437–1448CrossRefGoogle Scholar
  30. 30.
    N. Holroyd and G. Scamans (2013) Metall. Mater. Trans. A, vol. 44A, pp. 1230–1253Google Scholar
  31. 31.
    Wu Y, Wang Y (2010) Theor. Appl Fract Mech 54(1):19–26.  https://doi.org/10.1016/j.tafmec.2010.06.011 CrossRefGoogle Scholar
  32. 32.
    M. Baydogan, H. Cimenoglu, S. Kayali and J. Rasty (2008) Metall Mater Trans A, vol. 39A, pp. 2470–2476Google Scholar
  33. 33.
    Zelinski A, Chryzanowski J, Warmuzek M, Gazda A, Jezierska E (2004) Influence of retrogression and reaging on microstructure, mechanical properties and susceptibility to stress corrosion cracking of an Al–Zn–Mg alloy. Mater Corros 55(2):77–87.  https://doi.org/10.1002/maco.200303710 CrossRefGoogle Scholar
  34. 34.
    Thakur A, Raman R, Malhotra S (2007) Hydrogen embrittlement studies of aged and retrogressed-reaged Al–Zn–Mg alloys. Mater Chem Phys 101(2–3):441–447.  https://doi.org/10.1016/j.matchemphys.2006.08.004 CrossRefGoogle Scholar
  35. 35.
    Hwang R, Chou C (1997) The study on microstructural and mechanical properties of weld heat affected zone of 7075-T651 aluminum alloy. Scr Mater 38(2):215–221.  https://doi.org/10.1016/S1359-6462(97)00472-7 CrossRefGoogle Scholar
  36. 36.
    Ugiansky G, Skolnick L, Steifel S (1969) Directional effects in the stress corrosion cracking of an aluminum alloy. Corrosion 25(2):77–86.  https://doi.org/10.5006/0010-9312-25.2.77 CrossRefGoogle Scholar
  37. 37.
    T. Borchers and W. Zhang, Fused-overlap zone in aluminum arc welds: tendency of formation and effect on corrosion, in Trends in Welding Research: 10th International Conference, Tokyo, 2016Google Scholar
  38. 38.
    Online Materials Information Resource - MatWeb (2018) Matweb.com [Online]. Available: http://www.matweb.com. Accessed 12 Feb 2018
  39. 39.
    T. Borchers and W. Zhang (2015) Welding methods and welded joints for joining high-strength aluminum alloys. USA Patent Application No.: 62/251,427Google Scholar
  40. 40.
    Blaber J, Adair B, Antoniou A (2015) Ncorr: Open-Source 2D Digital Image Correlation Matlab Software. Exp Mech 55(6):1105–1122.  https://doi.org/10.1007/s11340-015-0009-1 CrossRefGoogle Scholar
  41. 41.
    T. Borchers, A. Seid, W. Zhang, P. Shafer, S. Babu and D. Phillips, Stress corrosion cracking susceptibility of gas metal arc welded 7xxx series aluminum alloys, in Sheet Metal Welding Conference XVI, Detroit, 2014Google Scholar
  42. 42.
    Cooper K, Kelly R (2007) Crack tip chemistry and electrochemistry of environmental cracks in AA 7050. Corros Sci 49(6):2636–2662.  https://doi.org/10.1016/j.corsci.2006.12.001 CrossRefGoogle Scholar
  43. 43.
    Sun X, Zhang B, Lin H, Zhou Y, Sun L, Wang J, Han E-H, Ke W (2014) Atom probe tomographic study of elemental segregation at grain boundaries for a peak-aged Al–Zn–Mg alloy. Corros Sci 79:1–4.  https://doi.org/10.1016/j.corsci.2013.10.027 CrossRefGoogle Scholar
  44. 44.
    Galvele J (1981) Transport processes in passivity breakdown—II. Full hydrolysis of the metal ions. Corros Sci 21(8):551–579.  https://doi.org/10.1016/0010-938X(81)90009-3 CrossRefGoogle Scholar

Copyright information

© International Institute of Welding 2018

Authors and Affiliations

  1. 1.Department of Materials Science and EngineeringThe Ohio State UniversityColumbusUSA
  2. 2.Honda R&D Americas, Inc.RaymondUSA

Personalised recommendations