Investigation of hydrogen evolution and enrichment by scanning Kelvin probe force microscopy

•SKPFM was employed to characterize the surface potential induced by hydrogen.•The work function decreased due to the presence of hydrogen.•The real-time distribution of hydrogen at the micro-level was detected.•Hydrogen enrichment and the crack propagation were observed by SKPFM.

It has been a challenge to detect the real-time distribution of hydrogen at the micro-level. In this study, a scanning Kelvin probe force microscopy (SKPFM) was employed to characterize the surface potential changes induced by hydrogen. Variations of the surface potential were used to assess (a) the real-time distribution of hydrogen, (b) hydrogen enrichment in reverted austenite and (c) hydrogen enrichment around the crack tip induced by the stress concentration.