Analyses of Microstructural and Chemical Effects on Fatigue Crack Growth

  • H. W. Liu
Conference paper

Abstract

Fatigue crack propagation is insensitive to micro-structure of a material in the intermediate ΔK region. But it is highly sensitive in the low ΔK near threshold region. da/dN decreases with ΔK. As ΔK decreases below a transition point, ΔKt, da/dN decreases rapidly, and a crack ceases to propagate when ΔK is below ΔKth.

A fatigue crack may propagate by the deformation or fracture mode or by a mixture of the two. Fatigue crack propagation in deformation mode is structurally insensitive if the cyclic plastic zone is several times the grain size or the size of the mean free path for dislocation movement when the crack tip deformation can be described in terms of the “average” yield strength of the material.

FCP in deformation mode is structurally sensitive, if the cyclic plastic zone is nearly the size of the grain or the mean free path of dislocation movement; and FCP in fracture mode is also structurally sensitive.

Intergranular fatigue crack growth by the fracture mode in detrimental chemical environment is structurally sensitive. The temperature and frequency effects of the crack growth in detrimental chemical environment as well as the relation between ΔKt and ΔKth are analyzed.

Keywords

Fatigue Crack Plastic Zone Crack Growth Rate Fatigue Crack Growth Fracture Mode 
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.
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Copyright information

© Martinus Nijhoff Publishers, The Hague 1983

Authors and Affiliations

  • H. W. Liu
    • 1
  1. 1.Syracuse UniversitySyracuseUSA

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