Residual Stresses
Residual stresses are internal mechanical stresses that occur without external load and are caused by uneven heating, cooling, or deformation. These stresses can lead to cracks and fractures.
Physico-chemical mechanism of action
Residual stresses arise from uneven heating or cooling of metals. Different parts of the material heat up at different rates, leading to stress zones. These stresses can also arise from mechanical deformations such as welding or forging.
Metallurgical relevance & risks in welding
Residual stresses can lead to cracks and fractures in the weld, especially if not properly balanced. Uneven cooling can cause the material to coarsen or contract differently, creating additional stresses. These stresses can cause hot cracking or fracture, especially in high-strength steels.
Workshop practice & action instructions
To minimize residual stresses and avoid risks, it is important to ensure uniform heating and cooling of the material. This can be achieved by proper selection of welding method and parameters. Extra care is needed with steels high in carbon or other stress-inducing elements. It is also important to cool the material slowly and evenly after welding to avoid the formation of residual stresses.