The distribution of H trapped at defects was visualized by means of a H micro-print technique. A low-C steel having a ferrite/pearlite structure with second phases along grain boundaries was subjected to notch-tensile and three-point bending tests with/without H pre-charging. The H micro-printing was applied to tested specimens re-charged with H. Accumulation of H was confirmed in strain-concentrated areas as well as along grain boundaries and in pearlite. A noteworthy finding was a substantial increase in defects acting as traps of diffusive H when specimens were deformed in the presence of H. The increased defects were annealed out at as low as 150C; indicating their point defect

highly strained areas such as near grain boundaries and the fracture surface, where T autoradiography revealed the evolution of defects having high binding energy with H.

nature. Another finding was the appearance of a zone denuded of Ag precipitation in Detection of Hydrogen Trap Distribution in Steel using a Microprint Technique. T.Ohmisawa, S.Uchiyama, M.Nagumo: Journal of Alloys and Compounds, 2003, 356-357, 290-4