Corrosion failure of marine steel in sea‐mud containing sulfate reducing bacteria

Abstract

The corrosion failure behavior of marine steel is affected by stress, which exists in offshore structures at sea-mud region. The sulfate reducing bacteria (SRB) in the sea-mud made the steel more sensitive to stress corrosion cracking (SCC) and weaken the corrosion fatigue endurance. In this paper, a kind of natural sea-mud containing SRB was collected. Both SCC tests by slow strain rate technique and corrosion fatigue tests were performed on a kind of selected steel in sea-mud with and without SRB at corrosion and cathodic potentials. After this, the electrochemical response of static and cyclic stress of the specimen with and without cracks in sea-mud was analyzed in order to explain the failure mechanism. Hydrogen permeation tests were also performed in the sea-mud at corrosion and cathodic potentials. It is concluded that the effect of SRB on environment sensitive fracture maybe explained as the consequences of the acceleration of SRB on corrosion rate and hydrogen entry into the metal.

Comparison of corrosion rates obtained from laboratory and field data

“…There are other aquatic factors influencing corrosion: salinity, pH‐value, acid capacity, and water hardness . Moreover, in case of sheet pile steels in nature, there can be mechanical influences such as water movement and biochemical effects like microbial‐induced corrosion (MIC) .…”