Effects of Waveform and Cycle Period on Corrosion-Fatigue Crack Growth in Cathodically Protected High-Strength Steels

Abstract:

The processes involved in corrosion fatigue in general are briefly outlined, followed by a brief review of recent studies on the effects of cycle frequency (rise times) and electrode potential on crack-growth rates at intermediate ΔK levels for cathodically protected high-strength steels. New studies concerning the effects of fall times and hold times at maximum and minimum loads on crack-growth rates (for K_max values below the sustained-load SCC threshold) are presented and discussed. Fractographic observations and the data indicate that corrosion-fatigue crack-growth rates in aqueous environments depend on the concentration of hydrogen adsorbed at crack tips and at tips of nanovoids ahead of cracks. Potential-dependent electrochemical reaction rates, crack-tip strain rates, and hydrogen transport to nanovoids are therefore critical parameters. The observations are best explained by an adsorption-induced dislocation-emission (AIDE) mechanism of hydrogen embrittlement.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 211-216
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.211
• Online since: March 2014
• Authors: Mark Knop*, Nick Birbilis, Stan Lynch
• Keywords: Adsorption-Induced Dislocation-Emission (AIDE), Corrosion Fatigue, Cycle Period, Hydrogen Embrittlement, Mechanism, Nanovoids, Steel, Striations, Waveform

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