Effects of σ Phase on the SCC Susceptibility and the Hydrogen Embrittlement Susceptibility of Super Duplex Stainless Steel F55

While duplex stainless steel has excellent mechanical properties and corrosion resistance, intermetallic compounds called σ phase easily precipitate. In this study, SSRT was performed using specimens with different amounts of σ phase precipitation. In corrosive solution, specimens with precipitated σ phase tended to have a more pronounced decrease in ductility. Moreover, SSRT was performed in a similar corrosive solution while continuously charging hydrogen by cathodic charging method. As a result, there was no correlation between the amounts of σ phase precipitation and mechanical properties. Therefore, the σ phase is considered to promote SCC while not promoting hydrogen embrittlement.