Mechanical Residual Stress
Mechanical residual stress arises from plastic deformation and stays permanently locked in the material. If too high, it can lead to cracks and damage.
Physico-chemical mechanism of action
Mechanical residual stress occurs when a material is plastically deformed – i.e., bent or stretched. This deformation changes the atomic structure of the material and creates stresses that don't go away, even after the deformation stops.
Metallurgical relevance & risks when welding
Mechanical residual stress can cause cracking and damage, especially when it's too high. When welding parts that are already under high stress, the stress can't be relieved and leads to hot cracking or breaking of the weld. It also affects the microstructure and mechanical properties of the material.
Workshop practice & instructions for action
To minimize mechanical residual stress, when processing by bending, cutting, or pressing pay close attention to proper strain and speed. When welding parts under high stress, it's important to ensure slow cooling (often through controlled cooling or heat exchangers) and to check the weld for cracks or distortion.