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The influence of microstructure and strength on the fracture mode and toughness of 7XXX series aluminum alloys

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Abstract

The effects of microstructure and strength on the fracture toughness of ultra high strength aluminum alloys have been investigated. For this study three ultra high purity compositions were chosen and fabricated into 1.60 mm (0.063 inches) sheet in a T6 temper providing a range of yield strengths from 496 MPa (72 ksi) to 614 MPa (89 ksi). These alloys differ only in the volume fraction of the fine matrix strengthening precipitates (G. P. ordered + η′ ). Fracture toughness data were generated using Kahn-type tear tests, as well asR-curve andJ c analyses performed on data from 102 mm wide center cracked tension panel tests. Consistent with previous studies, it has been demonstrated that the toughness decreases as the yield strength is increased by increasing the solute content. Concomitant with this decrease in toughness, a transition in fracture mode was observed from predominantly transgranular dimpled rupture to predominantly intergranular dimpled rupture. Both quantitative fractography and X-ray microanalysis clearly demonstrate that fracture initiation for the two fracture modes occurred by void formation at the Cr-dispersoids (E-phase). In the case of intergranular fracture, void coalescence was facilitated by the grain boundary η precipitates. The difference in fracture toughness behavior of these alloys has been shown to be dependent on the coarseness of matrix slip and the strength differential between the matrix and precipitate free zone (σM-σPFZ). A new fracture mechanism has been proposed to explain the development of the large amounts of intergranular fracture observed in the low toughness alloys.

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References

  1. J. A. Nock and N. Y. Hunsicker:J. Metals, 1963, vol. 15, no. 3, p. 216.

    CAS  Google Scholar 

  2. D. S. Thompson and R. E. Zinkham:Eng. Fract. Mech., 1975, vol. 7, p. 389.

    Article  CAS  Google Scholar 

  3. G. T. Hahn and A. R. Rosenfield:Metall. Trans. A, 1975, vol. 6A, p. 653.

    CAS  Google Scholar 

  4. M. Graf and E. Hornbogen:Acta Met., 1977, vol. 25, p. 883.

    Article  Google Scholar 

  5. A. H. Geisler:Phase Transformation in Solids, R. Smoluckowski, J. E. Mayer, and W. A. Weyl, eds., Wiley, New York, NY, 1951, p. 387.

    Google Scholar 

  6. J. L. Taylor:J. Inst. Met., 1963/64, vol. 92, p. 301.

    Google Scholar 

  7. N. Ryum:Acta Met., 1968, vol. 16, p. 327.

    Article  CAS  Google Scholar 

  8. S. Kirman:Metall. Trans., 1971, vol. 2, p. 1761.

    CAS  Google Scholar 

  9. P. N. T. Unwin and G. C. Smith:J. Inst. Met., 1969, vol. 97, p. 299.

    CAS  Google Scholar 

  10. R. H. Van Stone, R. H. Merchant, and J. R.Low, Jr.:ASTM STP 556, 1974, p. 93.

    Google Scholar 

  11. D. Broek:Eng. Fract. Mech., 1973, vol. 5, p. 55.

    Article  CAS  Google Scholar 

  12. J. T. Staley: Alcoa Technical Center, Alcoa Center, PA, unpublished research, 1974.

  13. B. J. Dunwoody, D. M. Moore, and A. T. Thomas:J. Inst. Met., 1973, vol. 101, p. 172.

    CAS  Google Scholar 

  14. J. M. Dowling and J. W. Martin:Proceedings of the Third International Conference on the Strength of Metals and Alloys, Institute of Metals and The Iron and Steel Institute, London, 1973, p. 170.

    Google Scholar 

  15. G. Lutjering and A. H. Gysier:Verformungsmechanismen und Struktur in der plastischen Zone vor Risspitzen, Seminarbericht 20 kV -Hochspannungselektronenmikroskopie, Munich, 1974, p. 9.

  16. G. Lutjering: Ruhr-Universitat Bochum, Institut fur Werkstoffe, Bochum, Germany, unpublished research, 1976.

  17. T. Mori and T. Mura:Mat. Sci. Eng., 1976, vol. 26, p. 89.

    Article  Google Scholar 

  18. D. Broek:NLR TR 72 029-u, National Aerospace Labs, The Netherlands, 1972.

    Google Scholar 

  19. R. H. Van Stone and J. A. Psioda:Metall. Trans. A, 1975, vol. 6A, p. 668.

    Google Scholar 

  20. J. S. Santer:Metall. Trans. A, 1978, vol. 9A, p. 769.

    Google Scholar 

  21. T. M. F. Ronald and D. P. Voss: Metals and Ceramics Synthesis Branch, Wright Patterson Air Force Base, OH, unpublished research.

  22. J. C. W. Van der Kastelle and D. Broek:Eng. Fract. Mech., 1911, vol. 9, p. 625.

    Article  Google Scholar 

  23. G. M. Ludtka and D. E. Laughlin:Metall. Trans. A, 1981, vol. 12A, p. 2083.

    Google Scholar 

  24. ASTM E8-69,Annual Book of ASTM Standards, 1969, vol. 31, p. 196.

  25. N. A. Kahn and E. A. Imbenbo:The Welding Journal, 1958, vol. 27, p. 169-s.

    Google Scholar 

  26. J. G. Kaufman and J. F. Reedy: “Description and Procedure for Making Kahn-Type Tear Tests,” Alcoa Laboratories Report, no. 9-M-681, Alcoa Technical Center, Alcoa Center, PA, February 10, 1966.

    Google Scholar 

  27. J. G. Kaufman and M. Holt:Advances in Cryogenic Engineering, 1965, vol. 10, p. 216.

    Google Scholar 

  28. J. G. Kaufman and A. H. Knoll:Mat. Res. and Standards, 1964, vol. 4, p. 151.

    Google Scholar 

  29. J. G. Kaufman and E. W. Johnson:ASTM Proceedings, 1963, vol. 62, p. 778.

    Google Scholar 

  30. R. H. Heyer:ASTM STP 381, 1965, p. 113.

  31. J. G. Kaufman and E. W. Johnson:Advances in Cryogenic Engineering, 1963, vol. 8, p. 678.

    CAS  Google Scholar 

  32. M. P. Hanson, G. W. Stickley, and H. T. Richards:ASTM STP 287, 1960, p. 3.

  33. ASTM E561-76T,Annual Book of ASTM Standards, 1976, vol. 31, p. 539.

  34. G. M. Ludtka: Ph.D. Thesis, Carnegie-Mellon University, Pittsburgh, PA, 1978.

    Google Scholar 

  35. J. R. Rice:J. Appl. Mech., 1968, vol. 35, p. 379.

    Google Scholar 

  36. J. A. Begley and J. D. Landes:ASTM STP 514, 1972, p. 1.

  37. K. G. Broberg:J. Mech. Phys. Solids, 1971, vol. 19, p. 407.

    Article  Google Scholar 

  38. J. P. Hickerson, Jr.:Eng. Fract. Mech., 1977, vol. 9, p. 76.

    Google Scholar 

  39. W. R. Warke, N. A. Neilson, R. W. Hertzberg, M. S. Hunter, and M. Hill:ASTM STP 436, 1968, p. 212.

  40. R. H. Van Stone and T. B. Cox:ASTM STP 600, 1976, p. 5.

  41. R. J. Price and A. Kelly:Acta Met., 1964, vol. 12, p. 979.

    Article  CAS  Google Scholar 

  42. G. I. Taylor:J. Inst. Met., 1938, vol. 62, p. 307.

    Google Scholar 

  43. A. Gysier, S. Lutjering, and V. Gerold:Acta Met., 1974, vol. 22, p. 901.

    Article  Google Scholar 

  44. G. Gutjering and S. Weissman:Acta Met., 1970, vol. 18, p. 785.

    Article  Google Scholar 

  45. J. D. Evensen, N. Ryum, and J. D. Embury:Mat. Sci. Eng., 1975, vol. 18, p. 221.

    Article  CAS  Google Scholar 

  46. E. Hornbogen and K. H. zum Gahr:Metallography, 1975, vol. 8, p. 181.

    Article  CAS  Google Scholar 

  47. J. Albrecht and G. Lutjering:Einfluss der Mikrostruktur auf die Ermudungsrissausbreitung in Aluminum-Legierungen, Forschungsbericht der Deutchen Luft-und Raumfahrt, DLR-EB77-07, Cologne, 1977.

  48. T. H. Sanders, Jr., E. A. Ludwiczak, and R. R. Sawtell:Mat. Sci. Eng., 1980, vol. 43, p. 247.

    Article  CAS  Google Scholar 

  49. K. Welpmann, G. Lutjering, and W. Bunk:Fracture 1977, 2, ICF4, Waterloo, Canada, June 19–24, 1977.

  50. R. B. Nicholson: “Strong Microstructures from the Solid State,” inStrengthening Methods in Crystals, A. Kelly and R. B. Nicholson, eds., Halsted Press, New York, NY, 1971, p. 553.

    Google Scholar 

  51. G. T. Hahn and A. R. Rosenfield:ASTM STP 432, 1968, p. 5.

  52. N. E. Paton and A. W. Sommer:Proceedings of the Third International Conference on the Strength of Metals and Alloys, Institute of Metals and The Iron and Steel Institute, London, 1973, p. 106.

    Google Scholar 

  53. I. J. Polmear:J. Inst. Met., 1960, vol. 89, p. 51.

    CAS  Google Scholar 

  54. M. M. Shea and B. V. N. Rao: “Influence of Ultrasonic Treatment on the Substructure in 304 Stainless Steel,” GM Research Publication GMR-3404, September 1980.

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Authors and Affiliations

  1. General Motors Research Laboratories, 48090, Warren, MI

    Gerard M. Ludtka (Senior Research Engineer)

  2. Carnegie-Mellon University, 15213, Pittsburgh, PA

    David E. Laughlin (Associate Professor of Metallurgical Engineering and Materials Science)

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  1. Gerard M. Ludtka
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  2. David E. Laughlin
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Formerly a Research Assistant at Carnegie-Mellon University

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Ludtka, G.M., Laughlin, D.E. The influence of microstructure and strength on the fracture mode and toughness of 7XXX series aluminum alloys. Metall Trans A 13, 411–425 (1982). https://doi.org/10.1007/BF02643350

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  • DOI: https://doi.org/10.1007/BF02643350

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