The mechanism of hydrogen-induced pitting corrosion in duplex stainless steel studied by SKPFM

The influence of the hydrogen charging on the pitting corrosion in duplex stainless steel was investigated by the scanning Kelvin probe PROBE force microscopy. The Volta potential maps of the hydrogen charged sample revealed that some low potential areas emerged at the ferrite/austenite boundaries or inside the ferrite phases, which may be considered as preferential nucleation sites of pitting corrosion induced by hydrogen. Moreover, a continuous evolution of Volta potential images indicated that the effects of hydrogen on ferrite and austenite were different due to different hydrogen behavior in two phases, which was confirmed by the work function of ferrite and austenite.

► The effect of hydrogen charging on the pitting in DSS was studied by SKPFM.
► The low-potential areas occur in the ferrite/austenite boundaries or inside ferrite.
► These areas may be considered as the nucleation sites of pitting induced by hydrogen.
► The continuous evolution of Volta potential after hydrogen charging was observed.
► The images exhibit the effects of hydrogen on ferrite and austenite were different.