Open Access

ARTICLE

An Evaluation of Fatigue Crack Growth in a Reactor Steel in Air and Aqueous Environments Considering Closure Effects

Ivo Černý¹, Václav Linhart²

1 SVÚM a.s., Strength Department, Areál VÚ, Podnikatelská 565, 19011 Praha 9, Czech Republic. Tel.: + 420 222724098; Fax:+420 22724509; Email: Ivo.Cerny@seznam.cz
2 SVÚM a.s., Strength Department, Areál VÚ, Podnikatelská 565, 19011 Praha 9, Czech Republic. Email: strength@svum.cz

Structural Durability & Health Monitoring 2009, 5(1), 73-86. https://doi.org/10.3970/sdhm.2009.005.073

Abstract

The experimental programme described in the paper was aimed at an evaluation of fatigue crack growth (FCG) rate and threshold conditions in a reactor pressure vessel steel in laboratory air and in simple aqueous environment. Though the main target of the work was to enlarge the data basis for possible future needs of defect and risk assessment, an emphasis was put on an evaluation of crack growth mechanisms. It was shown that despite some recent works infirming crack closure phenomenon itself or methods of its evaluation, crack closure explained near-threshold fatigue crack behaviour in the specific case of the reactor steel in air conditions and it was in a direct consistency with results of fractographical analyses. As regards corrosion fatigue crack growth (CFCG) in water saturated with O2, investigated at room temperature and atmospheric pressure, the CFCG rates were surprisingly significantly lower in comparison with air conditions. It was shown that strong closure effect was responsible for such the behaviour. An evaluation of CFCG rates as a dependence on effective value of stress intensity factor ∆K_eff enabled to show a strong acceleration effect of aqueous environment.

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