Hydrogen-induced crack
A hydrogen crack is a cold crack caused by diffusible hydrogen under tensile stresses. It often appears only hours or days after welding.
Physical-Chemical Mechanism of Action
Hydrogen-induced cracking occurs through the diffusion of hydrogen into the metal and its embrittlement under tensile stresses. This process can be slow, so cracks may appear only later.
Metallurgical Relevance & Welding Risks
Hydrogen-induced cracking can lead to severe cold cracks that damage the material and impair its mechanical properties. They contribute to cracking that appears later, making inspection and evaluation more difficult.
Workshop Practice & Action Guidelines
To avoid hydrogen-induced cracking, the metal should be thoroughly washed before welding. After welding, careful cooling is required to minimize tensile stresses. For special materials, the use of dehydrogenation treatments may also be recommended.