Abstract
Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack (“pop-in” vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies (E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (<0.2 wt pct) are typically ranging from 80 to 85 kJ/mol, whereas for high-copper-containing alloys (>~0.8 wt pct), they are typically ranging from 20 to 40 kJ/mol for under- and peak-aged alloys, and based on limited data, around 85 kJ/mol for over-aged tempers. This means that crack propagation in saline environments is most likely to occur by a hydrogen-related process for low-copper-containing Al-Zn-Mg-Cu alloys in under-, peak- and over-aged tempers, and for high-copper alloys in under- and peak-aged tempers. For over-aged high-copper-containing alloys, cracking is most probably under anodic dissolution control. Future stress corrosion studies should focus on understanding the factors that control crack initiation, and insuring that the next generation of higher performance Al-Zn-Mg-Cu alloys has similar longer crack initiation times and crack propagation rates to those of the incumbent alloys in an over-aged condition where crack rates are less than 1 mm/month at a high stress intensity factor.
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References
J.H. Mulherin: Stress Corrosion Testing, ASTM-STP 425, Philadelphia, PA, 1967, pp. 66-81.
A.J. McEvily, J.B. Clark and A.P Bond: Trans. ASM, 1967, vol. 60, pp. 661-71.
R. Shipp: Research Report A1747, The British Non-Ferrous Metal Research Association, London, October 1969.
M.V. Hyatt: Reports DC-24466, DC-24467, DC-24469, DC-24470, The Boeing Company, Seattle, November 1969.
M.V. Hyatt: Corrosion, 1970, vol. 26, pp. 487-503.
A.H. Le and R.T. Foley: Corrosion, 1983, vol. 39, pp. 379-83.
H.F. de Jong: Aluminium, 1981, vol. 11, pp. 526–31.
L.R. Hall, R.W. Finger, and W.F. Spurr: Report AFML-TR-73-204, The Boeing Company, Seattle, September, 1973.
M.O. Speidel: in The Theory of Stress Corrosion Cracking in Alloys, J.C. Scully, ed., NATO, Brussels, Belgium, 1971, pp. 298–344.
S.P. Knight: Ph.D. Thesis, Monash University, Melbourne, 2008.
S.P. Lynch, S.P. Knight, N. Birbillis, and B.C. Muddle: in Effects of Hydrogen in Metals, B. Somerday, P. Sofronis, and R. Jones, eds., ASM International, Materials Park, 2009, pp. 243–50.
D.O. Sprowls, M.B. Shoemaker, J.D. Walsh, and J.W. Coursen: Final Report, Prepared for George C. Marshall Space Flight Center, Alabama, Contract No. NAS-8021487-Part 1, May 31, 1973.
J.D. Kaufman, J.W Coursen, and D.O. Sprowls: ASTM-610, H.L. Craig, Jr., ed., ASTM, Philadelphia, PA, 1976, pp. 94–107.
K.L. Deffenbaugh: United States Naval Academy Trident Scholar Report No. 304, April 2003.
M. Cook, R. Chadwick, N.B. Muir: J. Inst. Met., 1951, vol. 79, pp. 293-320.
L.H. Chambers and D.C. Baxter: Engineer, 1967, vol. 223, pp. 518–20.
K.G. Kent: Metall. Rev., 1970, vol. 15(147), pp. 135–46.
W. Gruhl: Aluminium, 1978, vol. 54, pp. 323–25.
K.R. Anderson: U.S. Patent 5,312,498, May 17, 1994.
N.J.H. Holroyd: in Environment-Induced Cracking of Metals, R.P Gangloff and M.B Ives, eds., NACE, Houston, TX, 1990, pp. 311–45.
C.M. Liao: Corrosion, 1993, vol. 49, pp. 52-59.
S. Lee, S.L. Pyun, and Y. Chun: Metall. Trans. A, 1991, vol. 22A, pp. 2407-14.
S. Pyun, M. Hong and H. Kim: Br. Corros J., 1991, vol. 26, pp. 260-64.
N.J.H. Holroyd and D. Hardie: Corros. Sci., 1983, vol. 23, pp. 527-46.
L.P. Huang, K.H. Chen, S. Li and M. Song: Scripta Mater., 2007, vol. 56, pp. 305-08.
J.E. Finnegan and W.H. Hartt: in Stress Corrosion—New Approaches, ASTM-STP 610, H.L. Craig, ed., ASTM, Philadelphia, PA, 1976, pp. 44–60.
J.K Park: Mater. Sci. Eng., 1988, vol. A103, pp. 223-31.
E.C.H. Pow: Master’s Thesis, University of Minnesota, 1979.
E.C.H. Pow: Ph.D. Thesis, University of Minnesota, 1982.
S. Osaki, D. Itoh and M Nakai: J. Jpn. Inst. Light Met., 2001, vol. 51, pp. 222-27.
B. Jegdic and B. Bobic: Zastita Mater. 2007, vol. 48, pp. 14-18.
M.O. Speidel, R. Machler, and R. Magdowski: in 3rd International Conference on Aluminum Alloys (ICAA3), L. Arnberg, O. Lohne, E. Ness, and N. Ryum, eds., Trondheim, Norway, 1992, pp. 461–66.
N.J.H. Holroyd and D. Hardie: Met. Technol., 1982, vol. 9, pp. 229-34.
R.C. Doward and K.R. Hasse: Final NASA Report Contract No. NAS8-30890, Oct. 1976.
J. Robinson and P. Flynn: 1995, Key Engineering Materials, Vols. 99-100, pp. 143-50.
B.J. Connelly, M.G. Koul and A. L. Moran: Corrosion, 2005, vol. 61, pp. 976-86.
B. Sakar, M. Marek and E. A. Starke: Metall. Trans. A, 1981, vol. 12A, pp. 1939-43.
M. Landkof and L. Gal-Or: Corrosion, 1980, vol. 36, pp. 241-46.
R.S. Pathania and D. Tromans: Metall. Trans. A, 1981, vol. 12A, pp. 607-12.
T. Oka, K. Take, Y. Minamino, K. Hirao and T. Yamane: J. Jpn. Inst. Light Met., 1986, vol. 36, pp. 15-21.
H. Kim and S. Pyun: Taehan Kumsok Hakhoe Chi, 1984, vol. 22, pp. 621-31.
H. Gruhl: Z. Metallkunde, 1962, vol. 53, pp. 670-75.
S. Pyun: Metall, 1984, vol. 38, pp. 229-31.
H.B. Romans and H.L. Craig: Stress Corrosion Testing, ASTM-STP 425, Philadelphia, PA, 1966, pp. 363–78.
W.J. Helfrich: Stress Corrosion Testing, ASTM-STP 425, Philadelphia, PA, 1966, pp. 21–30.
Y. Choi, H.C. Kim, and S. Pyun: J. Mater. Sci., 1984, vol. 19, pp. 1517-21.
M.O. Speidel and M.V. Hyatt: Advanced Corrosion Science Technology, vol. 2, Plenum Press, New York, NY, 1972, pp. 115–335.
J. Onoro and C. Ranninger: J. Mater. Sci., 1999, vol. 35, pp. 509-14.
K. Komai, K. Minoshima, and H. Yukimachi: J. Soc. Mater. Sci. Jpn., 1983, vol. 32, pp. 1238–42.
S. Ohsaki, Y. Kojima and T. Takahashi: J. Jpn. Inst. Light Met., 1983, vol.33, pp. 579-87.
S. Osaki: Yomaguchi Daigaku Kogakubu Kenkyu Hokou, 1977, vol. 27 (2), 269–76.
M.O. Speidel: Metall. Trans. A, 1975, vol. 6A, pp. 631-51.
T. Ohnishi, H. Kojuma, N. Seko and K. Higashi: J. Jpn. Inst. Light Met., 1986, vol. 36, pp. 272-78.
J. Onoro, A. Moreno and C. Ranninger: J. Mater. Sci., 1989, vol. 24, pp. 3888-91.
F.S. Bovard: Master’s Thesis, University of Pittsburgh, 2005.
G.M. Scamans, M.F. Frolish, W.M. Rainforth, Z. Zhou, Y. Liu, X. Zhou and G.E. Thompson: Surf. Interface Anal., 2010, vol. 42., pp. 175-79.
T.H. Nguyen and R.T. Foley: J. Electrochem. Soc., 1980, vol. 127, pp. 2563–66.
A. Berzin, R.T. Lowson and K.J. Mirams: Aust. J. Chem., 1977, vol. 30, pp. 1891-1903.
D.M. Drazic, S.K. Zecevic, R.T. Atanasoski and A.P. Despic: Electochima Acta., 1983, vol. 28, pp. 751-55.
P.M. Natishan, W.E. Grady, E. McCafferty, D.E. Ramaker, K. Pandya and A. Russell: J. Eletrochem. Soc., 1999, vol. 146, pp. 1737-40.
A. Kolics, A.S. Besing, P. Baradlai, R. Haasch and A. Wieckowski: J. Electrochem. Soc., 2001, vol. 148, pp. B251-B259.
L. Tomcsanyi, K. Varga, I. Bartik, G. Horanyi and E. Malczki: J. Electrchim. Acta, 1989, vol. 34, pp. 885-89.
N.J.H. Holroyd and M.R. Jarrett: “Corrosion Chemistry within Pits, Crevices and Crack 2,” Unpublished Research, Presented at Conference held at Mansfield College, Oxford, UK, 2009.
N.J.H. Holroyd, G.M. Scamans, and R. Hermann: in Corrosion Chemistry within Pits, Crevices and Cracks, A. Turnbull, ed., HMSO, London, England, 1987, pp. 495–510.
N.J.H. Holroyd, G.M. Scamans, and R. Hermann: in Embrittlement by the Localized Environment, R.P. Gangloff, ed., AIME, Warrendale, PA, 1984, pp. 327–47.
M.S. Domak: in Environmentally Assisted Cracking: Science and Engineering, ASTM-STP 1049, W.B Lisagor, T.W. Crocker and B.N. Leis, eds., ASTM, Philadelphia, PA, 1990, pp. 391–409.
K.R. Cooper and R.G. Kelly: in Chemistry and Electrochemistry of Stress Corrosion cracking: A Symposium Honoring the Contributions of R.W. Staehle, R.H. Jones, ed., TMS, Warrendale, PA, 2001, pp. 523–42.
A. Turnbull: Corrosion, 2001, vol. 57, pp. 175-89.
S. Mostovoy, P.B. Crosley and E.J. Ripling: J. Mater., 1967, vol. 2, pp. 661-81.
H.R. Smith and D.E. Piper: Report D6-24872, The Boeing Company, Seattle, June 1979.
K.P. Wong and R.C. Alkire: J. Electrochem. Soc., 1990, vol. 137, pp. 3010-15.
Z.A Foroulis and M.J Thubrilar: J. Electrochem. Soc., 1975, vol. 122, pp. 1296-301.
R.T. Foley and T.H. Nguyen: J. Electrochem. Soc., 1982, vol.129, pp. 464-67.
R.T. Foley: Corrosion, 1986, vol. 42, pp. 277-88.
N.J.H. Holroyd: in Environmental Effects on Engineered Materials, R.S Jones, ed., Marcel Decker, Inc., New York, 2000, pp. 173–251.
F.E. Watkinson and J.C. Scully: Corrosion Science, 1972, vol. 12, pp. 905-24.
A.H. Le and R.T. Foley: Corrosion, 1984, vol. 40, pp. 195-97.
R.C. Doward and K.R. Hasse: Corrosion Science, 1979, vol. 19, pp. 131-40.
Y. Jiang: Final Office of Naval Research Report, Contract – N00014-08-0646, April 2011.
J. Zhang, S. Kalnaus, M. Behrooz and Y. Jiang: Metall. Mater. Trans. A, 2011, vol. 42A, pp. 448-60.
B.J. Connelly, K.L. Deffenbaugh, M.G. Koul, and A.L. Moran: JOM, 2003, vol. 55, pp. 49-52.
A.K Vasudevan and K. Sadananda: Metall. Mater. Trans. A., 2011, vol. 42A, pp. 396-404.
L.M Young: Ph.D. Thesis: University of Virginia, Charlottesville, VA, 1999.
K.R. Cooper, L.M. Young, R.P. Gangloff and R.G. Kelly: Materials Science Forum, 2000, Vol 331-337, pp. 1625-34.
L.M. Young and R.P. Gangloff: in Advances in the Metallurgy of Aluminum Alloys, M. Tiryakioglu, ed., ASM International, Materials Park, OH, 2001, pp. 135–40.
K.R. Cooper and R.G. Kelly: in Advances in the Metallurgy of Aluminum Alloys, M. Tiryakioglu, ed., ASM International, Materials Park, OH, 2001, pp. 73–82.
K.R. Cooper and R.G. Kelly: Corrosion Science, 2007, vol. 49, pp. 2636-62.
K.R. Cooper and R.G. Kelly: J. Chromatogr. A., 1999, vol.850, pp. 381–89.
T.H. Nguyen, B.F. Brown and R.T Foley: Corrosion, 1982, vol.38, pp. 319-26.
G.A Young and J.R. Scully: Metall. Mater. Trans. A., 2002, vol. 33A, pp. 101-15.
K. Kitamura and E. Sato: J. Jpn. Inst. Light Met., 1979, vol. 29, pp. 563-67.
A.S. Tetelman and A.J. McEvily, Fracture of Structural Materials, Wiley, New York, 1967, pp. 438-40.
G.M. Scamans: Metall. Trans. A, 1980, vol. 11A, pp. 846-50.
P. Martin, J.I. Dickson and J.P. Bailon: Mater. Sci. Eng., 1985, vol. 69, pp. L9-L13.
N.J.H. Holroyd and G.M Scamans: Metall. Mater. Trans. A., 2011, vol. 42A, pp. 3979-98.
C.J. Newton and N.J.H. Holroyd: in New Methods for Corrosion Testing Aluminum Alloys, ASTM-STP 1134, V.S. Agarwala and G.M. Ugiansky, eds., ASTM, Philadelphia, PA, 1992, pp. 153–79.
C.A. Loto and R. A. Cottis: Corrosion, 1989, vol. 45, pp. 136-41.
M.S. Domack: in Corrosion Cracking, V.S Groel, ed., ASM, Materials Park, OH, 1986, pp. 191–96.
J.P. Nordin, D.J. Sullivan, B.L. Phillips and W.H. Case: Inorg. Chem., 1998, vol. 37, pp. 4760–63.
D.J. Sullivan, J.P. Nordin, B.L. Phillips and W.H. Casey: Geochim. Cosmochim. Acta, 1999, vol. 63, pp. 1471-80.
M. Watanabe: J. Phys. Chem. Solids, 2010, vol. 71, pp. 1251-58.
T. Magnin, A. Chambreuil and B. Bayle: Acta Mater., 1996, vol. 44, pp. 1457-70.
M. Abe, K. Ouchi, K. Asano and A. Fujiwara: J. Jpn. Inst. Met., 1981, vol. 45, pp. 1161-69.
T.H. Sanders and E.A. Starke: Metall. Trans. A, 1976, vol. 7A, pp. 1407-18.
E.A. Starke: Mater. Sci. Eng., 1977, vol. 29, pp. 99-115.
F.S. Lin and E.A. Starke: Mater. Sci. Eng., 1979, vol. 39, pp. 27-41.
S.W. Ciaraldi, J.L. Nelson, R.A. Yeske and E.N. Pugh: Hydrogen Effects in Metals, I.M. Bernstein and A.W. Thompson, eds., AIME, Warrendale, PA, 1981, pp. 437–47.
R. Hermann: Corrosion, 1988, vol. 44, pp. 685-90.
F.P. Ford: Corrosion, 1979, vol. 35, pp. 281-89.
N. Lampeas and P.G. Koutoukos: Corros. Sci., 1994, vol. 36, pp. 1011–025.
M. Metikos-Hukovic, R. Babic, Z. Grubac and S. Brinic: J. Appl. Chem., 1994, vol. 24, pp. 325-31.
B. Bavarian, L. Reiner, H. Youssefpour, and I. Juraga: in Corrosion 2005—Paper #65329, NACE, Houston, 2005.
O.D. Sherby, J.L. Lytonn and J.E. Dorn: Acta Metall., 1957, vol.5, pp. 219-27.
T. Ishikawa and R.B. McLellan: Acta Metall., 1986, vol.34, pp. 1091-95.
G.A. Young and J.R. Scully: Acta Mater., 1998, vol. 18, pp. 6337-49.
J.R. Scully, G.A. Young and S.W. Smith: Materials Science Forum, 2000, vols. 331-337, pp. 1583-600.
S. Ohsaki, Y. Kojima and T. Takahashi: J. Jpn. Inst. Light Met., 1983, vol.33, pp. 539-46.
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Holroyd, N.J.H., Scamans, G.M. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments. Metall Mater Trans A 44, 1230–1253 (2013). https://doi.org/10.1007/s11661-012-1528-3
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DOI: https://doi.org/10.1007/s11661-012-1528-3