Macroscopic Residual Stresses of the First Kind
Macroscopic residual stresses of the first kind are mechanical stresses spread over larger component volumes, arising from uneven plastic deformation or temperature differences. They can affect strength and material behavior under load.
Physical-Chemical Mechanism of Action
Macroscopic residual stresses of the first kind arise from inhomogeneous plastic deformation or thermal gradients within the material. These stresses are distributed over larger volumes as mechanical forces built up inside the material.
Metallurgical Relevance & Welding Risks
These stresses can critically affect component strength and lead to cracking or distortion. During welding, the material may become stressed due to uneven plastic deformation during cooling, potentially causing hot cracking or weld failure.
Shop Practice & Action Guidelines
To minimize macroscopic residual stresses of the first kind, it's important to ensure uniform cooling of the component. This can be achieved through controlled cooling methods such as cooling walls or cooling sources. When welding, the weld length and material should be selected so that plastic deformation is evenly distributed. The cooling time should not be too short to avoid stress, but also not too long to avoid over-stressing the material.