Corrosion and fatigue characteristics of positively polarised Zeron 100 base & weld metal in synthetic seawater

It is envisaged that super duplex stainless steels, as currently used in the offshore oil and gas industries, will find application in the emergent renewable energy sector in areas such as offshore wind, wave and tidal electricity/hydrogen generation. Such applications typically involve engineering components experiencing fluctuating loads in a harsh environment such as seawater. In these circumstances, there is a real possibility of increased crack growth rates due to combined corrosion fatigue. In this way, the current paper investigates the corrosion and fatigue characteristics of Zeron 100 weld metal in synthetic seawater. High-imposed electrochemical potentials are specifically addressed, since it is well known that aerated and chlorinated seawater in contact with high alloy stainless steels give rise to high local electrochemical potentials. The corrosion resistance of the weld metal was similar to the base metal when positively polarised in synthetic seawater at ambient temperature. Crack propagation rates increased for the base and weld metal by over a factor of 2 compared to rates in laboratory air. High temperature solution significantly reduces the pitting potential and delays repassivation.