Ratcheting Effect
The ratcheting effect is a creeping deformation of materials under repeated loading with mean stress. It leads to long-term geometric changes and shortens service life.
Physicochemical mechanism of action
The ratcheting effect occurs when a material is subjected to cyclic tension-compression loading with mean stress. The asymmetric loading leads to microscopic deformations that accumulate over time, resulting in progressive material deformation.
Metallurgical relevance & welding risks
Ratcheting can occur in welded joints, especially at high mean stresses or under long-term cyclic loading. It leads to long-term deformation of the weld and can reduce the mechanical strength and service life of the material. This increases the risk of cracking and fracture.
Workshop practice & instructions
To minimize ratcheting, the following measures should be taken:
• Use suitable materials with low stress sensitivity in welding.
• Keep the mean stress as low as possible during welding.
• Avoid long-term cyclic loading and optimize the use of welded joints.