Mass Spectrometer Measurements of the Diffusion Coefficient of Hydrogen in Steel in the Temperature Range of 25°–90°C

Abstract

The diffusion coefficients for hydrogen in mild steel have been measured in the temperature range of 25° to 90°C. A mass spectrometer was used to study the movement of hydrogen through thin steel plates. Two methods of measuring diffusion have been used; the rate of approach to equilibrium when hydrogen is supplied to the plate, and the rate of outgassing when the source of hydrogen is removed. Two decidedly different sets of diffusion coefficients were obtained by the two methods. The first method gave diffusion coefficients which agree very well with values obtained by others at higher temperatures while the outgassing method, which was more reproducible, gave values considerably lower. These results are compared with those of other investigators.