Neutron radiography study of hydrogen desorption in technical iron

The purpose of the present study is to show the feasibility of examining hydrogen desorption in technical iron samples using neutron radiography at the ANTARES facility of the FRM II research reactor, Technische Universität München. It has been shown that this method is appropriate for in situ determination of hydrogen desorption for concentrations as low as 20 ppm_H. Experiments were carried out in the temperature range from room temperature up to 260 °C. Measurement was based on direct comparison between electrochemically hydrogen-loaded iron samples and hydrogen-free reference samples at the same temperature. This enables the determination of hydrogen concentration as a function of time and temperature. Ex situ carrier gas hot extraction experiments using the same temperature?Ctime profiles as the neutron radiography experiments have been used to calibrate the greyscale values of the radiographs to defined hydrogen concentrations. It can be stated that hydrogen desorption correlates with sample temperature.