Thermal Stresses
Thermal stresses arise from uneven temperature distributions during heating or cooling of steels. They can cause plastic deformation or cracking.
Physical-Chemical Mechanism of Action
During welding, thermal stresses arise when different parts of a component reach different temperatures. This can be caused by uneven heat diffusion or different materials.
Metallurgical Relevance & Risks in Welding
Thermal stresses can lead to plastic deformation of the steel, which distorts and makes the components ductile. In extreme cases, they can cause cracks or hot cracks in the weld or in the component. This can be a problem especially with high-strength or precipitation-hardened steels such as martensite or austenite.
Workshop Practice & Action Guidelines
To minimize thermal stresses, it is important to carry out controlled heating and cooling (HAG). This can be achieved by using protective layers, correct selection of the welding process, or the application of stress measurements. For steels with high structural hardness, slow cooling (often overnight) is recommended to avoid the occurrence of cracks.