Residual Stress of the Second Kind
Residual stress of the second kind are microscopic stresses between grains that arise from uneven deformation. They influence the flow of the material.
Physico-chemical mechanism of action
Residual stresses of the second kind occur when adjacent crystallites or grains are deformed differently. These stresses are microscopic and act across the boundaries of individual grains.
Metallurgical relevance & risks in welding
Residual stresses of the second kind can lead to micro-strain states, which harden the material and impair its toughness. They increase the risk of cracks and wear. In the weld, this can lead to increased susceptibility to hot cracking and cold cracking.
Workshop practice & action instructions
To minimize residual stresses of the second kind, it is important to ensure uniform deformation of the material during welding. This can be achieved by correct selection of welding parameters and control of cooling steps. An optimal cooling rate (t8/5) of 10 to 20 seconds is often recommended to obtain a uniform grain structure.