Critical Crack Length
Critical crack length is the maximum extent of a crack before unstable fracture occurs. It determines the safety of components.
Physical-chemical mechanism of action
Crack length describes how far a crack can extend in a material before it suddenly and unstably fractures under the applied stress. This process is called a brittle fracture.
Metallurgical relevance & risks in welding
At too high stress levels or insufficient hardness, a crack can reach its maximum crack length and suddenly break. This leads to catastrophic cracks that can cause further destruction.
Workshop practice & action instructions
To increase the crack length and minimize the risk of brittle fractures, it is important to achieve sufficient hardness in the weld. This can be ensured by correct heat treatment and selection of the right steel. In highly stressed components, stresses should be controlled and hardness checked.