Fatigue Crack Initiation
Fatigue crack initiation is the beginning of cyclic fracture, where microscopic cracks form through microplastic slip processes. This phase determines the service life under high cycle counts.
Physical-chemical mechanism of action
Fatigue crack initiation occurs when metals undergo microplastic deformation under repeated mechanical loads. This deformation leads to microscopic cracks on the surface or at inhomogeneities in the material. With each further load cycle, these cracks grow and can eventually lead to complete fracture.
Metallurgical relevance & risks during welding
Fatigue phenomena are especially dangerous in weld areas because they often contain inhomogeneities or uneven stresses. These can accelerate crack initiation and significantly shorten the service life of components. Under high cycle counts, this can lead to sudden failures, which is especially dangerous in critical applications.
Workshop practice & procedures
To avoid or minimize fatigue crack initiation, the following measures should be taken:
• Use high-quality welding consumables with low susceptibility to cracking.
• Ensure that weld areas are evenly loaded and that no uneven stresses occur.
• Apply proper cooling techniques to stabilize the material's structure.
• Avoid excessive mechanical loads and conduct regular inspections.