Comparative investigation of electrolytic hydrogenation of pipe assortment steel under cathodic polarization

Abstract

Comparative studies of electrolytic hydrogenation of pipe steels in NS4 electrolytes under cathodic polarization were carried out. It was established that the dependence of hydrogen concentration penetrating through steel under cathodic polarization in the NS4 electrolyte on the polarization potential is nonlinear, and differs for steels of different chemical compositions. Hydrogenation of pipe steels resulted in changes in their electrochemical properties. Null current potential tends to shift to more negative values as the cathodic polarization potential increases (by absolute value) from −0.75 V to −1.2 V. Polarization resistance of the partial anodic reaction for all steels increases non-monotonically with different intensities. A dependence diagram of hydrogenating from the steel strength under cathodic polarization is drawn and analyzed. It was established that at the minimum protective potential of −0.75 V, hydrogenation of all the steels is not happening. At a potential of −0.95 V, the maximal hydrogenation is observed for steel with the lowest ultimate strength, and at the maximum protective potential of −1.05 V – hydrogenation susceptibility changes non-monotonically. Under more cathodic polarization at a potential of −1.2 V, steel 09G2S with the lowest ultimate strength hydrogenated most strongly, and steels with similar ultimate strength indicators have a similar tendency to hydrogen penetration.