Experimental Mechanics

, Volume 13, Issue 1, pp 1–6 | Cite as

Brittle fracture of precompressed steel as affected by hydrostatic pressure, temperature and strain concentration

Paper presents a demonstration and explanation of how moderate strain concentration converts gradual changes in response with pressure, temperature, or strain rate to an abrupt brittle-to-ductile transition
  • R. H. Hawley
  • D. C. Drucker
Article

Abstract

Highly precompressed 1020 HR steel, 0.65 prestrain at 400°F (204°C), tested in nominally uniform tension at −80°F (−62°C) fractures at about 110,000 psi (760 MN/m2) with less than 0.02 plastic strain. Yet the addition of a hydrostatic pressure of less than 7000 psi (48 MN/m2) converts this visually brittle fracture to a ductile one with appreciable necking. The explanation of this surprising experimental result is shown to follow directly and simply from the combination of a tensile stress criterion of fracture, strain concentration and the low tangent modulus of the stress-strain curve in tension beyond the Bauschinger transition region of a few percent of plastic strain. Temperature dependence and strain-rate dependence of brittle fracture similarly are predictable in an almost trivial manner from the appropriate stress-strain curves for different amounts of precompression. So also is the amazingly high ductility or fracture toughness of the most complex of perforated or notched statically loaded structures of mild steel in an undamaged or fully annealed state.

Keywords

Ductility Fracture Toughness Fluid Dynamics Tensile Stress Plastic Strain 

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References

  1. 1.
    Drucker, D. C., “An Evaluation of Current Knowledge of the Mechanics of Brittle Fracture”, Ship Structure Committee Report SSC-69 (1954).Google Scholar
  2. 2.
    Mylonas, C., “The Mechanics of Brittle Fracture”,Proc. 11th Intn'l. Cong. of Appl. Mech. H. Gortler, ed., Springer, Berlin, 652–660 (1964).Google Scholar
  3. 3.
    Drucker, D. C., “A Continuum Approach to the Fracture of Metals”, Fracture of Solids, D. C. Drucker and J. J. Gilman, eds., Interscience-Wiley, 3–50 (1963).Google Scholar
  4. 4.
    Drucker, D. C. “Macroscopic Fundamentals in Brittle Fracture”, Treatise on Fracture, H. Liebowitz, ed., ch. 8, Academic Press, 473–531 (1968).Google Scholar
  5. 5.
    Mylonas, C. andRockey, K. C., “Exhaustion of Ductility by Hot Straining—An Explanation of Fracture Initiation Close to Welds”,The Welding J.,40,Research Supplement,306s-310s (1961).Google Scholar
  6. 6.
    Körber, F., Eichinger, A. andMöller, H., “Verhalten Gestauchter Metalle bei ZugbeanspruchungKaiser Wilhelm Institut fur Eisenforschung, Pt. I, 23, 123–133 (1941);Pt.II, 26, 71–89 (1943). Also, Drucker, D. C., Mylonas, C. and Lianis, G., “On the Exhaustion of Ductility of E-Steel in Tension Following Compressive Prestrain”, The Welding J.,39,Research Supplement 117s–120s (1960).Google Scholar
  7. 7.
    Ludley, J. H. andDrucker, D. C., “A Reversed Bend Test to Study Ductile to Brittle Transition”,The Welding J.,39,Research Supplement,543s-546s (1960).Google Scholar
  8. 8.
    Mylonas, C., Kobayashi, S. andArmenakas, A. E., “Exhaustion of Ductility under Notch Constraint Following Uniform PrestrainingTrans. Metallurgical Soc. of AIME,245,919–927 (1969).Google Scholar
  9. 9.
    Kobayashi, S. and Mylonas, C., “Exhaustion of Ductility in Compressed Bars with Holes”, Ship Structure Committee Report SSC-184 (1968).Google Scholar
  10. 10.
    Mylonas, C., “Exhaustion of Ductility and Brittle Fracture of E-Steel Caused by Prestrain and Aging”, Ship Structure Committee Report SSC-162 (1964).Google Scholar
  11. 11.
    Bridgman, P. W., “Studies in Large Plastic Flow and Fracture”,McGraw-Hill, NY (1952).Google Scholar
  12. 12.
    Brandes, M., “Studies in Large Plastic Flow of Cast Iron Specimens Stretched Under Hydrostatic Pressures up to 17500 kg/cm 2”,Intn'l. J. of Fracture Mech.,3,175–182 (1967).Google Scholar
  13. 13.
    Galli, J. R. andGibbs, P., “The Effect of Hydrostatic Pressure on the Ductile-Brittle Transition in Molybdenum”,Acta Metallurgica,12,775–778 (1964).CrossRefGoogle Scholar
  14. 14.
    Hendrickson, J. A., Wood, D. S. andClark, D. S., “The Initiation of Brittle Fracture in Mild Steel,”Trans. ASM,50,656–681 (1958).Google Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1973

Authors and Affiliations

  • R. H. Hawley
    • 1
  • D. C. Drucker
    • 2
  1. 1.Brown UniversityProvidence
  2. 2.College of EngineeringUniversity of IllinoisUrbana

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