Abstract
In an aged Ti-8.6 wt pct Al alloy macroscopic embrittlement occurs with increasing grain size and degree of age hardening. The influence of the grain sizeL on the true fracture strain can be described by εF ∼L-1 Tensile crack nucleation is caused microscopically by strong dislocation pile-ups which crack the grain boundaries. Using transmission electron microscopy and equations from the dislocation theory, an experimental method was developed to determine quantitatively the shear stress concentrations at the grain boundaries which are produced by the dislocation pile-ups and cause crack nucleation. The experimental results show that for all investigated grain sizes and degrees of age hardening a critical local stress t* C ≈ 38 GPa leads to crack nucleation. Based on this result equations were derived which describe the combined influence of grain size and age hardening on the true fracture strain and on the true fracture stress. These equations show a good agreement with the tensile test results.
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G. Lütjering: European Space Agency, TT-245, 1976.
H. Gleiter and E. Hombogen:Mat. Sci. Eng., 1967-68, vol. 2, p. 285.
H. Gleiter and E. Hombogen:Phys. Stat. Sol., 1965, vol. 12, p. 235.
E. Hombogen and K. H. Zum Gahr:Metallography, 1975, vol. 8, p. 181.
G. Lütjering and S. Weissman:Acta Met., 1970, vol. 18, p. 785.
E. Hombogen and G. Lutjering:6th Intern. Conf. on Light Metals, Leoben/Vienna, 1975, Aluminium Verlag Dusseldorf, 1975, p. 40.
A. Gysler, G. Lütjering, and V. Gerold:Acta Met. 1974, vol. 22, p. 901.
A. Gysler, G. Terlinde, and G. Lütjering: in “Proc. of the 3rd Intern. Conf. on Titanium”, Moscow, May 1976, Plenum Press, New York, NY, 1981.
K. H. Zum Gahr and L. J. Eberhartinger:Z. Metallkde., 1967, vol. 67, p. 1835.
M. G. Mendiratta, S. M. L. Sastry, and J. V. Smith:J. Mat. Sci., 1976, vol 11, p. 1835.
G. Lütjering, T. Hamajima, and A. Gysler: in “Fracture 1977”Proceedings of the 4th Intern. Conf. on Fracture, Waterloo, Canada, 1977, p. 4.
E. Nes:Z. f. Metallkde., 1978, vol. 69, p. 35.
M. Peters and G. Lütjering:Z. f. Metallkde, 1976, vol. 67, p. 811.
E. Hombogen and M. Graf:Acta Met., 1977, vol. 25, pp. 887 and 883.
A. H. Cottrell:Trans. TMS-AIME, 1958, vol. 212, p. 192.
M. J. Blackburn and J. C. Williams:Trans. ASM, 1969, vol. 62, p. 398.
M. J. Blackburn:Trans. TMS-AIME, 1967, vol. 239, p. 1200.
D. J. Truax and C. J. McMahon, jr.:Mat. Sci. Eng., 1974, vol. 13, p. 125.
K. R. Evans:Trans. TMS-AIME, 1969, vol. 245, p. 1297.
G. Welsch, G. Lütjering, K. Gazioglu, and W. Bunk:Metall. Trans. A, 1977, vol 8A, p. 16.
M. J. Blackburn and J. C. Williams:Trans. TMS-AIME, 1967, vol. 238, p. 287.
J. D. Eshelby, F. C. Frank, and F. R. N. Nabarro:Phil. Mag., 1951, vol. 42, p. 351.
J. P. Hirth and J. Lothe:Theory of Dislocations, McGraw Hill, New York, NY, 1968, pp. 694–718.
G. Leibfried:Z. Physik, 1951, vol. 130, p. 214.
H. Conrad, M. Doner, and B. de Meester: in “Titanium Science and Technology”, Plenum Press, New York, NY, 1973, p. 966.
C. Zener: in “Fracturing of Metals”, ASM, Metals Park, OH, 1948, p. 125.
W. Meyer zur Capellen:Integraltafeln, Springer Verlag, Berlin, 1953, p. 76.
G. Terlinde: Dissertation, Ruhr-University Bochum, 1978.
S. Lee and J. C. M. Li: Univ. of Rochester, Rochester, NY 1980.
J. Lindigkeit, G. Terlinde, A. Gysler, and G. Lütjering:Acta Met., 1979, vol. 27, p. 1717.
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Terlinde, G., Luetjering, G. Influence of Grain Size and Age-Hardening on Dislocation Pile-Ups and Tensile Fracture for a Ti-AI Alloy. Metall Trans A 13, 1283–1292 (1982). https://doi.org/10.1007/BF02645512
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DOI: https://doi.org/10.1007/BF02645512