S-N curve
The Wöhler line shows the relationship between the applied fatigue stress and the number of cycles to failure. It helps engineers in designing dynamically loaded structures.
Physical-Chemical Mechanism of Action
The Wöhler curve describes how many load cycles a material can withstand before it fails. It shows the relationship between the fatigue stress (the maximum stress the material can take without plastic deformation) and the number of load cycles to fracture.
Metallurgical Relevance & Welding Risks
The Wöhler curve is critical for the safety of dynamically loaded structures. A material operating under too high stress or too many load cycles can suddenly fail and cause dangerous cracks. This can be especially relevant in welding when the weld is not strong enough.
Workshop Practice & Action Instructions
To make sure a structure is designed according to Wöhler curve criteria, engineers must consider the maximum allowable stress and the number of load cycles. In welding, this means the weld must be strong enough to carry the expected loads. This can be ensured by careful material selection and proper welding technique.