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.