Hydrogen Induced Cracking (HIC) occurs in carbon or low-alloy steels when atomic hydrogen diffuses into it and forms molecular hydrogen that connects adjacent hydrogen blisters on different planes in the metal, or to the metal surface. A HIC is the internal cracks brought about by material trapped in budding hydrogen atoms that diffuses into a metallic structure with atomic hydrogen, many alloys and metals may lose their mechanical properties in wet H2S process environments.
Reference Definition by Inspectioneering.com: A Hydrogen Induced Cracking (HIC) is a common form of wet H2S cracking caused by the blistering of a metal due to a high concentration of hydrogen. The blistering damage tends to form parallel to the surface and to the direction of hoop stress. HIC usually occurs due to the effects of aqueous hydrogen charging of steel in wet H2S refinery process environments. It can occur at relatively low temperatures, largely as a result of atomic hydrogen from wet H2S corrosion reactions which enter the steel and collect at inclusions or impurities within the steel.
Related Definitions in the Project: The Metallurgy (Corrosion and Cracking)
