MECHANISM OF CORROSION OF CARBON AND LOW-ALLOY FERRITIC STEELS BY HIGH-TEMPERATURE WATER

Experimental evidence indicates that up to 90% of all hydrogen is generated at the metal/oxide interface during corrosion in the absence of oxygen. None of the presently accepted mechanisms are able to account for this observation. After consideration of possible diffusion routes, a mechanism involving diffusion of H//2O and/or O**2** minus , H** plus , and Fe**2** plus is proposed. The relationship between the amount of magnetite deposited from solution onto the surface and the fraction of hydrogen generated at the metal/oxide interface is discussed.