Intergranular Cold Crack
A delayed crack in the heat-affected zone, promoted by diffusing hydrogen, a martensitic structure, and high residual stresses. It usually follows grain boundaries and can occur time-delayed after cooling.
Physical-Chemical Mechanism of Action
Intercrystalline cold cracking occurs due to the diffusion of hydrogen into the metal, especially if it has a martensitic structure. This process can occur during or after welding and leads to local stresses in the material. These stresses can increase over time and lead to cracks, usually along grain boundaries.
Metallurgical Relevance & Welding Risks
Intercrystalline cold cracking can cause severe hardness problems and cracks in the weld. It is especially dangerous because it can occur time-delayed after the material has already cooled. This can lead to unexpected failures during component operation.
Workshop Practice & Instructions
To avoid intercrystalline cold cracking, it is important to minimize hydrogen diffusion during welding. This can be achieved by using deoxidizers and careful cooling. The temperature in the heat-affected zone should be controlled to avoid a martensitic structure. For high-hydrogen materials, additional measures such as hydrogen removal methods or using low-hydrogen alloys should be considered.