Metallurgical and Materials Transactions A

, Volume 43, Issue 1, pp 87–107

Effects of Processing Residual Stresses on Fatigue Crack Growth Behavior of Structural Materials: Experimental Approaches and Microstructural Mechanisms

Article

Abstract

Fatigue crack growth mechanisms of long cracks through fields with low and high residual stresses were investigated for a common structural aluminum alloy, 6061-T61. Bulk processing residual stresses were introduced in the material by quenching during heat treatment. Compact tension (CT) specimens were fatigue crack growth (FCG) tested at varying stress ratios to capture the closure and Kmax effects. The changes in fatigue crack growth mechanisms at the microstructural scale are correlated to closure, stress ratio, and plasticity, which are all dependent on residual stress. A dual-parameter ΔKKmax approach, which includes corrections for crack closure and residual stresses, is used uniquely to connect fatigue crack growth mechanisms at the microstructural scale with changes in crack growth rates at various stress ratios for low- and high-residual-stress conditions. The methods and tools proposed in this study can be used to optimize existing materials and processes as well as to develop new materials and processes for FCG limited structural applications.

Nomenclature

a

crack length (measured from the center of specimen loading holes in the case of the compact tension (CT) specimen geometry)

B, W

compact tension (CT) specimen thickness and width

C, m

Paris regime fit parameters

C0

compliance in the absence of closure, above the opening load of a crack

Ci

(initial) compliance prior to the initiation of a crack

Cs

(secant) compliance of one compliance load-displacement record, including crack closure

K

nominal stress intensity

Kapp

applied stress intensity considering the effects of residual stresses

Kmax

nominal maximum stress intensity

Kmin

nominal minimum stress intensity

Kres

stress intensity caused by residual stress

ΔK

nominal stress intensity range

ΔKapp

applied stress intensity considering the effects of residual stresses

ΔKcl

stress intensity range under which the crack is partially to fully closed

ΔKeff

effective stress intensity range considering the effects of closure

n

degree of plane stress

N

number of cycles

rplastic

radius of the plastic zone ahead of the crack tip

R

nominal stress ratio

Rapp

applied stress ratio considering the effects of residual stresses

Reff

effective stress ratio considering the effects of closure

δ

displacement

σY

yield strength determined by 0.2 pct offset technique

References

  1. 1.
    G. Glinka: Fatigue and Fracture Mechanics, vol. 677, C.W. Smith, ed., American Society for Testing and Materials, West Conshohocken, PA, 1979, pp. 198–214.Google Scholar
  2. 2.
    A.P. Parker: Residual Stress Effects in Fatigue, vol. 776, H.S. Reemsnyder and J.F. Throop, eds., American Society for Testing and Materials, West Conshohocken, PA, 1982, pp. 13–31.Google Scholar
  3. 3.
    D.V. Nelson: Residual Stress Effects in Fatigue, vol. 776, H.S. Reemsnyder and J.F. Throop, eds., American Society for Testing and Materials, West Conshohocken, PA, 1982, pp. 172–94.Google Scholar
  4. 4.
    Y.C. Lam and K.S. Liam: Theor. Appl. Fract. Mech., 1989, vol. 12, pp. 59-66.CrossRefGoogle Scholar
  5. 5.
    M. Beghini and L. Bertini: Eng. Fract. Mech., 1990, vol. 36, no. 3, pp. 379-87.CrossRefGoogle Scholar
  6. 6.
    S.R. Daniewicz, J.A., Collins, and D.R. Houser: Int. J. Fatigue, 1994, vol. 16, pp. 123-33.CrossRefGoogle Scholar
  7. 7.
    R.J. Bucci: Fatigue and Fracture Mechanics, vol. 743, R. Roberts, ed., American Society for Testing and Materials, West Conshohocken, PA, 1981, pp. 28–47.Google Scholar
  8. 8.
    D.L Chen, B. Weiss, and R. Stickler: Mater. Sci. Eng. A, 1996, vol. 208A, pp. 181-87.Google Scholar
  9. 9.
    F. Bergner, G. Zouhar, and G. Tempus: Int. J. Fatigue, 2001, vol. 23, pp. 383-94.CrossRefGoogle Scholar
  10. 10.
    L.P. Borrego, J.M. Costa, and F.V. Antunes: Eng. Fail. Anal., 2010, vol. 17, pp. 11-18.CrossRefGoogle Scholar
  11. 11.
    L.P. Borrego, J.M. Costa, and S. Silva: Int. J. Fatigue, 2004, vol. 26, pp. 1321-31.CrossRefGoogle Scholar
  12. 12.
    D.H. Lee, J.H. Park, and S.W. Nam: Mater. Sci. Technol., 1999, vol. 15, pp. 450-55.Google Scholar
  13. 13.
    R. Scheffel and K. Detert: Fracture Control of Engineering Structures, H.C. Van Elst and A. Bakker, eds., EMAS Publications, Warrington, UK, 1986, pp. 1511–21.Google Scholar
  14. 14.
    R.H. Christensen: Appl. Mater. Res., 1963, vol. 2, no. 4, pp. 207-10. Google Scholar
  15. 15.
    W. Elber: Eng. Fract. Mech., 1970, vol. 2, pp. 37-45.CrossRefGoogle Scholar
  16. 16.
    J.C. Newman Jr.: J. Eng. Mater. Technol., 1995, vol. 117, pp. 433-39.CrossRefGoogle Scholar
  17. 17.
    S. Suresh and R.O. Ritchie: Fatigue Crack Growth Threshold Concepts, D.L. Davidson and S. Suresh, eds., TMS-AIME, Warrendale, PA, 1984, pp. 227–61.Google Scholar
  18. 18.
    J.K. Donald, G.H. Bray, and R.W. Bush: Fatigue and Fracture Mechanics, vol. 1332, T.L. Panontin and S.D. Sheppard, eds., American Society for Testing and Materials, West Conshohocken, PA, 1998, pp. 674–95.Google Scholar
  19. 19.
    P.C. Paris, H. Tada, and J.K. Donald: Int. J. Fatigue, 1999, vol. 21, pp. S47-S57.CrossRefGoogle Scholar
  20. 20.
    D.A. Lados, D. Apelian, and J.K. Donald: Int. J. Fatigue, 2007, vol. 29, no. 4, pp. 687-94.CrossRefGoogle Scholar
  21. 21.
    A.K. Vasudevan and K. Sadananda: Metall. Mater. Trans. A, 1995, vol. 26A, pp. 1221-34.CrossRefGoogle Scholar
  22. 22.
    ASTM Standard E647, 2005, “Standard Test Method for Measurement of Fatigue Crack Growth Rates,” ASTM International, West Conshohocken, PA, 2005. DOI:10.1520/E0647-05, www.astm.org.
  23. 23.
    D.A. Lados and D. Apelian: Eng. Fract. Mech., 2006, 73, vol. 4, pp. 435–55.Google Scholar

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2011

Authors and Affiliations

  1. 1.George W. Woodruff School of Mechanical Engineering, Georgia Institute of TechnologyAtlantaUSA
  2. 2.Department of Material Science and EngineeringWorcester Polytechnic InstituteWorcesterUSA

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