Accession Number:

ADA043368

Title:

Organizational Scheme for Corrosion-Fatigue Crack Propagation Data.

Descriptive Note:

Interim rept.,

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s):

Report Date:

1977-07-01

Pagination or Media Count:

100.0

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 attackannihilation, 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 G21 is developed, combining attributes of both, which seems to successfully describe the corrosion induced augmentation of G2.

Subject Categories:

  • Properties of Metals and Alloys
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE