Fatigue Crack Growth
Fatigue crack propagation is the continuous growth of a crack under repeated mechanical loading. It is described by the Paris law.
Physical-chemical mechanism of action
Under alternating mechanical loading, e.g. under cyclic loads, cracks can continuously grow in materials. This process is called fatigue crack growth. The growth rate of the crack depends on the load amplitude and the number of load cycles.
Metallurgical relevance & risks during welding
Fatigue cracks can lead to critical failures, such as rupture or crack propagation. In the welding field, this means that incompletely closed cracks or poor weld quality can continue to grow under repeated loading and eventually lead to complete failure.
Workshop practice & procedures
To avoid fatigue cracks, it is crucial that weld quality is high. This means that the weld is fully closed and that there are no incomplete cracks or gaps. Additionally, under cyclic loading, regular inspections should be carried out to detect and repair fatigue cracks early.