Alternating Stress
Cyclic loading: Stresses alternate regularly between tensile and compressive, which can lead to fatigue failure.
Physical-Chemical Mechanism of Action
Alternating stress occurs when a component or weld is regularly subjected to alternating tensile and compressive stresses. This leads to repeated stress cycles that damage the material structure.
Metallurgical Relevance & Risks in Welding
Alternating stress can cause cracks to form or existing cracks to propagate. The hardness of the material increases, leading to crack-sensitive microstructures. This can be particularly problematic for highly stressed components such as machine parts and load-bearing structures.
Workshop Practice & Instructions
To minimize alternating stress, components should be designed to allow even load distribution. When welding, it is important to ensure stress balance and to sufficiently stress-relieve the material before the load cycle.