Rest line
Latch lines are the macroscopic characteristic of a fatigue fracture , they reveal the cyclical crack growth on the fracture surface. They arise from corrosion at the end of the crack in the event of a long-term change in the mean voltage. This often changes when there is a change in the operating status, for example a plant shutdown overnight or a reversal of the direction of rotation. Depending on the material and environmental conditions, it takes between 30 minutes and a few days to create a visible stop line. If the operating conditions are recorded, the starting point of the crack can be estimated with the aid of the snap lines.
In the event of a vibration break, stop lines do not necessarily have to be recognizable. These only arise if there was not only a single-stage exposure.
Web links
- Technical reliability + damage analysis (accessed on October 14, 2019)
- Bolt "saves" the course of damage (accessed on October 14, 2019)
- Proceedings of the 1st Pforzheim Materials Day (accessed on October 14, 2019)