SEDL / STP / STP801-EB / STP44819S

A Theoretical Evaluation of the Oxygen Concentration in a Corrosion-Fatigue Crack

Turnbull, A
Senior Scientific Officer, National Physical Laboratory, Teddington, Middlesex,

Pages: 16    Published: Jan 1983

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Abstract

The oxygen concentration in a corrosion-fatigue crack has been evaluated theoretically by assuming that oxygen was consumed by cathodic reduction on the walls of the crack and mass transport occurred by diffusion and advection (forced convection), with the latter resulting from the sinusoidal variation of the displacement of the crack walls. By using parameters relevant to a compact tension specimen, the time-dependent distribution of the oxygen concentration in the crack was calculated as a function of ΔK (the range of the stress intensity factor), R-value (minimum load/maximum load), frequency, crack length, and electrode potential. The influence of advection was to significantly enhance the mass transport of oxygen in the crack compared with “diffusion-only” even at low frequencies and low ΔK. Regions in the crack were identified in which advection dominance or diffusion dominance of the mass transport of oxygen occurred.