STP801

    Crack Growth by Stress-Assisted Dissolution and Threshold Characteristics in Corrosion Fatigue of a Steel

    Published: Jan 1983


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    Abstract

    Corrosion-fatigue crack growth and the threshold characteristics of a high-tension steel HT55 (σB = 580 MPa) have been investigated in 1% NaCl solution by using an automated microcomputer-controlled K-device.

    Crack growth rates are significantly reduced in 1% NaCl solution at 5 Hz and R = 0.1, with a threshold value above the air values. The corrosion-products-induced wedge effect results in a reduced ΔK-value, thereby reducing growth rates. Therefore crack growth rates in 1% NaCl solution exceed those in air, with a lower threshold value than in air when considered in terms of ΔKeff.

    Supposing a linear summation hypothesis in terms of ΔKeff given by (da/dN)CF = (da/dN)F + (da/dN)D, the crack growth that proceeds by stress-assisted dissolution (da/dN)D is derived. A proposal to estimate long-term corrosion-fatigue crack growth characteristics is presented, where ΔKeff is assumed to be identical to ΔK since the crack tip is blunted and the crack is much thickened in long-term corrosion fatigue. The long-term corrosion-fatigue crack growth curves are finally derived at various stress cycle frequencies.

    Keywords:

    corrosion fatigue, crack growth rate, Δ, K, eff, corrosion-products-induced wedge effect, stress-assisted dissolution, long-term characteristics


    Author Information:

    Endo, K
    Professor, Associate Professor, and Graduate Student, Kyoto University, Kyoto,

    Komai, K
    Professor, Associate Professor, and Graduate Student, Kyoto University, Kyoto,

    Shikida, T


    Paper ID: STP44807S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP44807S


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