A HYDROGEN PERMEATION STUDY OF CYCLICALLY DEFORMED LOW-ALLOY STEEL

The effect of the dislocation arrangement on hydrogen permeation in spheroidized low alloy steel (German steel grade 90MnV8, Nr. 1.2842) was studied using the electrochemical permeation technique. The testing material was cyclically deformed in different gaseous environments (hydrogen and ultra-high vacuum) to obtain dislocation structures with different degrees of cell formation. For undeformed material used as a reference the density and mean binding energy of hydrogen traps were evaluated using the trapping theory. The dislocation cell structure formed during fatigue reduces the apparent diffusion coefficient as the trap density is increased. On the other hand, the steady state hydrogen permeation flux is increased as dislocation cores act as short diffusion paths.