Organizational Scheme for Corrosion-Fatigue Crack Propagation Data.
Abstract
A model, proposed earlier, is modified in an attempt to explain a number of curious behaviors of corrosion-fatigue crack propagation (CFCP). The behaviors include effects of load ratio R in air and salt water vs. vacuum, and effects of loading frequency at fixed R in these environments. Assumptions of the modelling are reviewed in detail in view of earlier objections to them. The ingredients of CFCP per this model: Poisson contraction, strain hardening, ligament surface attack/annihilation, and stress relaxation are developed and related to conditions of the crack-tip locale. In the modelling, a parameter G, for growth rate factor, is developed solely as a function of the form of the ordinary or of the cyclic stress-strain curve. Previous work had developed a G1 for the ordinary curve, to be associated with the surface attack effect as in stress-corrosion cracking, and one G2 for the cyclic curve to be associated with the stress relaxation effect as in fatigue crack propagation (FCP). A hybrid G2/1 is developed, combining attributes of both, which seems to successfully describe the corrosion induced augmentation of G2.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1977
- Accession Number
- ADA043368
Entities
People
- J. M. Krafft
- W. H. Cullen Jr.
Organizations
- United States Naval Research Laboratory