Quantification of the hydrogen produced during corrosion fatigue crack propagation

Modelling of environmentally assisted cracking depends on the ability to pr ovide quantitative information on the anodic dissolution and on hydrogen pr oduction at a crack tip. The amount of gaseous hydrogen produced during cor rosion fatigue crack propagation at the open circuit potential was measured on 316L stainless steel in MgCl2 solution at 117 degrees C. In situ monito ring of natural cracks was performed by using long focal length video optic al microscopy to measure hydrogen bubble diameters at the crack mouth. A bo undary condition of the hydrogen evolution inside a crack was obtained and, by considering the electrochemical reactions occurring inside a crack, a m inimum volume of metal dissolved per cycle at the crack tip was estimated. (C) 1999 Elsevier Science Ltd. All rights reserved.