Corrosion Behavior of Structural Steel under Ironmaking Dusts

Abstract

Steel structures in steel works are remarkably deteriorated by corrosion over time. Especially, severe corrosion has been observed in the place where dust of coking coal, coke, ore, and sinter ore, called ironmaking dust, is deposited. In order to prevent equipment failure and collapse caused by corrosion, it is necessary to give priority to equipment maintenance from the prediction of residual strength which can be calculated from the relation between residual plate thickness and corrosion rate. First, it is necessary to clarify the corrosion behavior of structural steels under ironmaking dust.

The corrosion loss of various dusts was evaluated in the exposure and laboratory tests, and it was found that the corrosivity of coke dust was extremely severe among the ironmaking dusts. From the polarization measurement, it was proven that this was caused by galvanic corrosion caused by the contact of coke dust, whose electric conductivity was increased by the dry distillation, with the structural steel material and worked as a cathode site.

When SUS304 or galvanized steel （GI） was used as a corrosion resistance material in this environment, SUS304 had a risk of breakdown of the passive film, and corrosion of galvanized steel （GI） was so severe that the zinc corrosion products could not exhibit the corrosion inhibition effect. Therefore, it is not preferable to apply these corrosion resistance materials under coke dust.