Abstract: The distribution of hydrogen near the notch tip of the austenitic steel 21Cr9Ni9MnN under mode Ⅰ loading has been studid with ion microprobe mass analyzer.Two peaks of hydrogen accumulation,one at notch tip and other far apart from it,were found.The distribution of hydrostatic stress and plastic strain in front of the notch tip under planar stress condition were calculated using ADINA non-linear finite element method.The calculated result in compari- son with data measured showed that the hydrogen concentration peak at the notch tip is caused by trapping effect of dislocation on dissolved hydrogen,while the other from the hydrostatic stress.The influence of stress intensity factor on the distribution of hydrogen con- centration and the process of hydrogen accumulation near notch tip was also discussed.

Key words: hydrogen accumulation peak, notch tip, ion microprobe mass analyzer, non-linear finite element method