Effect of hydrogen on pitting susceptibility of 2507 duplex stainless steel

The effect of hydrogen on pitting corrosion susceptibility of duplex stainless steel was investigated. Pits are observed on the hydrogen-charged specimen after 6 days of immersion in 6% FeCl3 solution, while no pits on the uncharged specimen even after more than 30 days of immersion, which indicates that hydrogen promotes pitting initiation and pit growth. Moreover, pitting susceptibility increases with hydrogen charging current density. The pitting tends to nucleate initially inside the austenite or at ferrite/austenite boundaries, and then appears in the ferrite, because of different behaviors of hydrogen in two phases, such as solubility and diffusivity of hydrogen.

► The effect of hydrogen on pitting corrosion susceptibility of duplex stainless steel (DSS) was investigated.
► Hydrogen promotes pit initiation and accelerates pit growth in DSS.
► Higher hydrogen concentrations give rise to higher pitting susceptibility.
► Pitting is more severe in acidic solution than in neutral one.
► Pits nucleate initially inside the austenite phase or at ferrite/austenite boundaries.