Detection of Hydrogen in a Steel at Elevated Temperatures by an Electrochemical Method

Abstract

An electrochemical permeation method using molten sodium hydroxide is presented to detect hydrogen in a steel at elevated temperatures (673-773 K) in the range of practical interest for hydrogen attack.
The results are as follows:
(1) The most suitable potential range to detect hydrogen is from -0.8 to -0.6 V vs Air/O^2- (ZrO₂).
(2) The experimental permeation curves for specimens with thickness above 4 mm agree fairly well with the theoretical ones.
(3) Diffusivities of hydrogen in the steel 6.5 mm thick in this study are in good agreement with the values obtained from a usual gaseous method.
(4) The detection limit of hydrogen content in the steel in this study is less than 0.1 ppm.
(5) Therefore, this electrochemical method will be useful to predict the hydrogen attack of steels.