Hydrogen Induced Cracking (HIC)
Definition - What does Hydrogen Induced Cracking (HIC) mean?
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. Typically, this diffusion of hydrogen is caused by the accidental introduction of hydrogen during the forming or finishing process of metal but hydrogen can be introduced at any time the metal is exposed to free hydrogen atoms or molecules and in metals affected with galvanic corossion.
Hydrogen induced cracking is also known as hydrogen embrittlement or hydrogen blistering.
Trenchlesspedia explains Hydrogen Induced Cracking (HIC)
For hydrogen induced cracking to take place, individual hydrogen atoms must cluster at the surface of the metal to create hydrogen molecules. This clustering produces pressure in the metal which results in the metal losing ductility, toughness and tensile strength. Over time, the metal becomes so brittle that it cracks. Though not limited to these materials, steel, iron, titanium and aluminum (only at high temperatures) are highly vulnerable to HIC.
Metals are more susceptible to hydrogen induced cracking at higher temperatures which explains why it is usually started during the forming or finishing process of the metal.
HIC can be prevented, or even reversed, through several process which focus on ensuring that no contact is made between the metal and hydrogen. Electroplating can prevent HIC, as can a process known as baking which can reverse the effects of hydrogen before the metal cracks.