What is hydrogen induced cracking?

Hydrogen induced cracking (HIC) is a type of material failure that occurs in metals due to the presence of hydrogen. HIC is also known as hydrogen embrittlement or hydrogen stress cracking. When hydrogen is present in the metal, it can diffuse into the atomic lattice, causing small voids or vacancies to form. These voids weaken the metal and can lead to cracking under stress.

HIC commonly occurs in materials used in oil and gas production, where hydrogen sulfide is present, as well as in industrial settings where acid cleaning is used. It can also occur in high-strength steels used in the automotive and aerospace industries, among others.

The prevention of HIC involves minimizing the presence of hydrogen during manufacturing, storage, and use of materials. This can be done by using low-hydrogen welding processes, limiting exposure to sources of hydrogen, and using materials that are less susceptible to HIC.

Testing for susceptibility to HIC can be done using specialized laboratory techniques, such as the delayed fracture test and the hydrogen permeation test, which measure the degree of hydrogen embrittlement in a material. Preventative measures such as stress-relieving heat treatments, cathodic protection, and the use of hydrogen-resistant coatings can also help to prevent HIC in materials.