Abstract
Hydrogen blistering was electrochemically induced on mild steel immersed in alkaline sour solution by cathodic reduction to study the onset of blistering. Test solution attempted to emulate that associated with water formed in catalytic cracking units of oil refinery plants with cyanide ions. Chronoamperometry method allowed blister diameter and density be tuned by potential pulses and testing time. A theoretical formula was used to calculate critical radius before blistering onset, assuming a depth for hydrogen implantation. A reasonable correlation was found between these measurements and those experimentally determined. The critical radius for blistering initiation seems to be ascribed to a stress higher than the yield stress of material. Blistering rupture displayed material tearing so that a ductile fracture appears to be a consequence of the aerostatic pressure of molecular hydrogen.
