Measurement of Hydrogen in High Strength Steels Using the Barnacle Electrode.

Abstract : The objectives of this program are to demonstrate the effectiveness of the barnacle electrode (BE) for measuring mobile hydrogen and to correlate the levels of such hydrogen with the tendency for delayed failure of two high strength steels, AISI 4340 at the 260-280 ksi (1793-1931 MPa) ultimate strength level and 300M at the 280-300 ksi (1931-2068 MPa) ultimate strength level. These steels were bright cadmium plated to introduce hydrogen into the substrate and then baked for periods of 2 to 100 hours. The notch stress rupture stress to produce failure in 200 hours was used to measure susceptibility to hydrogen embrittlement. The results indicate that the BE can effectively measure mobile hydrogen and susceptibility to delayed failure can be correlated with BE measurements. Confidence in the use of the BE system can be increased by delineating the cause for the observed variation in current density readings. (Author)