The effect of dynamic tensile straining on H permeation through low alloy Cr–Mo steel samples was studied with the electrochemical permeation technique. The H steady-state permeation current through large flat tensile specimens mounted between the two compartments of an electrochemical permeation cell undergoes different types of changes, depending on the charging conditions, on the steel’s composition and microstructure and on the strain rate. Dynamic trapping of H to strain-induced dislocations which led to a deviation of the permeation current below the initial steady-state value was mostly observed when the external H activity and the strain rate were large. However, the H permeation current through Cr–Mo steels with a bainitic microstructure appeared to be less sensitive to tensile straining up to large deformation levels than a lower alloyed Cr–Mo steel with a ferrito-pearlitic microstructure. On the other hand, the enhancement of the steady-state H permeation current observed during tensile straining if specific experimental conditions were met strongly suggested a mechanism of H transport by mobile dislocations which contributed to H permeation.

Influence of Tensile Straining on the Permeation of Hydrogen in Low Alloy Cr–Mo Steels. A.M.Brass, J.Chêne: Corrosion Science, 2006, 48[2], 481-97