Effect of Corrosion on Mass Loss, and High and Low Cycle Fatigue of Reinforcing Steel

Abstract

The effect of various levels of corrosion on the mass loss, and the high and low cycle fatigue of BSt500s steel reinforcement were experimentally investigated. The mass loss, the fatigue limit, and the life expectancy were reduced by 1.5 to 2.9%, 20 to 40%, and 56 to 76%, respectively, according to the corrosion level. Low cycle strain-controlled fatigue testing under a ±1% constant amplitude strain showed that the corroded steel bars exhibit a gradual reduction in the load-bearing ability, the available energy, and the number of cycles to failure. The considerable reduction in the fatigue limit took place because the mass loss led to a reduction of the exterior hard layer of martensite and a drastic drop in the energy density of the corroded specimens, thus developing stress concentration points that are highly localized at imperfections, and especially in the pits and notches of the rib bases of the corroded steel. Because corrosion and cycle fatigue are time-dependent, it seems that steel reliability is also time-dependent.