Metallurgical and Materials Transactions A

, Volume 40, Issue 2, pp 365–376 | Cite as

Experimental and Analytical Investigations on Plane Strain Toughness for 7085 Aluminum Alloy

  • R.T. Shuey
  • F. BarlatEmail author
  • M.E. Karabin
  • D.J. Chakrabarti


Data are presented on plane strain fracture toughness, yield strength, and strain hardening for three orientations of samples from quarter-thickness (t/4) and midthickness (t/2) locations of alloy 7085 plates with different gages aged past peak strength with different 2nd step aging times (T7X). These data are fit to an expression adapted from Hahn and Rosenfield (1968), in which toughness is proportional to strain hardening, the square root of yield strength, and the square root of a critical strain ε c . Strain-hardening exponent n is replaced by an alternative measure, since the stress-strain data do not follow a power law. With increased overaging, the increase of strain hardening dominates the decrease of strength, such that toughness increases. The critical strain, which represents the influence of the microstructure on toughness, has no trend with overaging time. Constituents and grain boundary precipitates, thought to be the microstructural elements most differentiating alloy 7085 from alloy 7050, are quantified at t/4 and at t/2 on one plate. From this the greater critical strain at t/2 than at t/4 is mainly attributed to greater effective spacing of constituents. Critical strain is also greater with longitudinal loading and crack propagating in the long transverse direction, but definite understanding of this will require better anisotropic fracture mechanics and further microstructural characterization.


Plastic Zone Critical Strain Linear Elastic Fracture Mechanic Uniform Elongation Plane Strain Fracture Toughness 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The authors gratefully acknowledge the contribution of their colleagues at Alcoa Technical Center: Messrs. J. Dalton and J. Brem for their assistance in mechanical testing, Mr. D.K. White for all the heat-treatment experiments, Mr. Paul Schwartz for SEM characterization, Dr. T.N. Rouns for the image analysis of grain boundary precipitates, and Dr. J. Boselli for reviewing the manuscript. Moreover, the authors thank Dr. M. Tiryakioglu (Robert Morris University) for his help in analyzing literature on microstructural models of toughness.


  1. 1.
    J.T. Staley: Materials Selection and Design, ASM, Materials Park, OH, 1997, pp. 381–89.Google Scholar
  2. 2.
    D.J. Chakrabarti, J. Liu, R.R. Sawtell, and G.B Venema: Proc. ICAA9, Institute of Materials Engineering Australasia Ltd., North Melbourne, 2004, pp. 969–74Google Scholar
  3. 3.
    J. Boselli, D.J. Chakrabarti, and R.T. Shuey: Proc. ICAA11, Wiley-VCH, Weinheim, 2008, in pressGoogle Scholar
  4. 4.
    S.A. Meguid: Engineering Fracture Mechanics, Elsevier Applied Science, New York, NY, 1989, p. 288Google Scholar
  5. 5.
    T.L. Anderson: Fracture Mechanics—Fundamental and Applications, CRC Press, Boca Raton, FL, 1995, p. 60Google Scholar
  6. 6.
    H. Tada, P.C. Paris, G.R. Irwin: The Stress Analysis of Cracks Handbook, 3rd ed., ASME, New York, NY, 2000Google Scholar
  7. 7.
    G.R. Irwin: Proc. 7th Sagamore Conf., Raquette Lake, NY, 1960, pp. 63–78.Google Scholar
  8. 8.
    Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials, Designation E399-90, ASTM, Philadelphia, PA, 1991Google Scholar
  9. 9.
    J.M. Krafft: Appl. Mater. Res., 1964, vol. 3, pp. 88–101Google Scholar
  10. 10.
    G.T. Hahn and A.R. Rosenfield: Applications Related Phenomena in Titanium Alloys, ASTM Special Technical Publication No. 432, ASTM, Philadelphia, PA, 1968, pp. 5–32Google Scholar
  11. 11.
    G.G. Garrett, J.F. Knott: Metall. Trans. A, 1977, vol. 9A, pp. 1187–1201ADSGoogle Scholar
  12. 12.
    R.K. Pandey, S. Banerjee: Eng. Fract. Mech., 1978, vol. 10, pp. 817–29CrossRefGoogle Scholar
  13. 13.
    R.O. Richie, W.L. Server, R.A. Wullaert: Metall. Trans. A, 1979, vol. 10A, pp. 1557–70ADSGoogle Scholar
  14. 14.
    C.J. Peel, P.J.E. Forsyth: Met. Sci., 1973, vol. 7, pp. 121–27CrossRefGoogle Scholar
  15. 15.
    M.P. Blinn, R.A. Williams: Materials Selection and Design, ASM, Materials Park, OH, 1997, pp. 536–38.Google Scholar
  16. 16.
    J.E. Hatch: Aluminum: Properties and Physical Metallurgy, ASM, Metals Park, OH, 1984. pp. 180–81Google Scholar
  17. 17.
    D.G. Altenpohl: Aluminum: Technology, Applications and Environment, TMS, Warrendale, PA, 1998, p. 135Google Scholar
  18. 18.
    M.F. Ashby: Materials Selection in Mechanical Design, Elsevier, Amsterdam, 2005Google Scholar
  19. 19.
    N. Kamp, I. Sinclair, M.J. Starink: Metall. Mater. Trans. A, 2002, vol. 33A, pp. 1125–36CrossRefGoogle Scholar
  20. 20.
    A. Deschamps, S. Esmaeili, W.J. Poole, M. Militzer: J. Phys. IV, 2000, vol. 10, pp. Pr6-151–Pr6-156CrossRefGoogle Scholar
  21. 21.
    L.M. Cheng, W.J. Poole, D.J. Embury, D.J. Lloyd: Metall. Mater. Trans. A, 2003, vol. 34A, pp. 2473–81CrossRefGoogle Scholar
  22. 22.
    D. Dumont, A. Deschamps, Y. Bréchet, C. Sigli, J.C. Ehrström: Mater. Sci. Technol., 2004, vol. 20, pp. 567–76CrossRefGoogle Scholar
  23. 23.
    J.T. Staley: Properties Related to Fracture Toughness, STP 605, ASTM, Philadelphia, PA, 1976, pp. 71–103.Google Scholar
  24. 24.
    D. Dumont, A. Deschamps, Y. Bréchet: Mater. Sci. Eng. A, 2003, vol. A356, pp. 326–36Google Scholar
  25. 25.
    N.U. Deshpande, A.M. Gokhale, D.K. Denzer, J. Liu: Metall. Mater. Trans. A, 1998, vol. 29A, pp. 1191–201CrossRefGoogle Scholar
  26. 26.
    P.T. Unwin, G.C. Smith: J. Inst. Met., 1969, vol. 97, pp. 299–310.Google Scholar
  27. 27.
    D. Embury, E. Nes: Z. Metallkd., 1974, vol. 65, pp. 45–55Google Scholar
  28. 28.
    E. Hornbogen: Z. Metallkd., 1975, vol. 66, pp. 511–13Google Scholar
  29. 29.
    G.M. Ludtka, D.E. Laughlin: Metall. Trans. A, 1982, vol. 13A, pp. 411–25.ADSGoogle Scholar
  30. 30.
    M.E. Karabin, F. Barlat, and R.T. Shuey: Metall. Mater. Trans. A, 2009, vol. 40A, DOI  10.1007/s11661-008-9705-0
  31. 31.
    J.R. Rice and M.A. Johnson: Inelastic Behavior of Solids, McGraw-Hill, New York, NY, 1970, pp. 641–72.Google Scholar
  32. 32.
    A. Pineau and T. Pardoen: Comprehensive Structural Integrity, Elsevier, New York, NY, 2007, vol. 2, pp. 757–59.Google Scholar
  33. 33.
    A.M. Gokhale, N.U. Deshpande, D.K. Denzer, J. Liu: Metall. Mater. Trans. A, 1998, vol. 29A, 1203–10CrossRefGoogle Scholar
  34. 34.
    D. Dumont, A. Deschamps, Y. Brechet: Acta Mater., 2004, vol. 52, pp. 2529–40CrossRefGoogle Scholar
  35. 35.
    N.U. Deshpande: Ph.D. Thesis, Georgia Institute of Technology, Atlanta, GA, 1996.Google Scholar
  36. 36.
    T. Pardoen, J.W. Hutchinson: Acta Mater., 2003, vol. 51, pp. 133–48CrossRefGoogle Scholar
  37. 37.
    X.S. Gao, T.H. Wang, J. Kim: Int. J. Solids Struct., 2005, vol. 42, pp. 5097–117.zbMATHCrossRefGoogle Scholar
  38. 38.
    D. Lassance, F. Scheyvaerts, T. Pardoen: Eng. Fract. Mech., 2006, vol. 73, pp. 1009–34.CrossRefGoogle Scholar
  39. 39.
    D. Broek: Eng. Fract. Mech., 1973, vol. 5, pp. 55–66.CrossRefGoogle Scholar
  40. 40.
    R.M. McMeeking: J. Mech. Phys. Solids, 1977, vol. 25, pp. 357–81CrossRefGoogle Scholar
  41. 41.
    A. Needleman, V. Tvergaard: J. Mech. Phys. Solids, 1987, vol. 35, pp. 151–83zbMATHCrossRefADSGoogle Scholar
  42. 42.
    V. Tvergaard, J.W. Hutchinson: J. Mech. Phys. Solids, 1992, vol. 40, pp. 1377–97zbMATHCrossRefADSGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2008

Authors and Affiliations

  • R.T. Shuey
    • 1
  • F. Barlat
    • 1
    • 2
    Email author
  • M.E. Karabin
    • 1
  • D.J. Chakrabarti
    • 1
    • 3
  1. 1.Alloy Technology and Materials Research DivisionAlcoa Technical CenterPittsburghUSA
  2. 2.Materials Mechanics Laboratory, Graduate Institute of Ferrous Technology (GIFT)Pohang University of Science and Technology (POSTECH)PohangRepublic of Korea
  3. 3.WoodsideUSA

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