An electrochemical permeation method was used to characterize hydrogen permeation properties of high strength microalloyed steel intended for sour service applications. Laboratory variations of steel microstructures with a similar strength level were also developed. These steel variations were achieved by means of accelerated cooling at
different rates changing cooling media. Tensile tests indicated that steel specimens had roughly the same yield strength level. Hence, the hydrogen embrittlement susceptibility of the material could be related to their permeation properties. The results indicated different behaviours over diffusivity and hydrogen solubility among microstructures. The increase of certain classical steel phases (bainite, ferrite, martensite, etc) together with numerous precipitates at the expense of dislocations led to such a change in permeability. The uniform distribution of strong hydrogen traps in some specimens instead of weak traps would impede the hydrogen transport toward a possible crack tip strained region in practice, thus, improving the resistance to sulphide stress corrosion cracking.