Submicroscopic Residual Stresses
Residual stresses of the third kind arise from local lattice stresses around dislocations or vacancies. They affect mechanical strength and can lead to cracking.
Physical-Chemical Mechanism of Action
Third-order residual stresses arise when dislocations or vacancies form in a crystal lattice. These local stresses alter the lattice structure and can lead to mechanical strengths or weaknesses.
Metallurgical Relevance & Risks in Welding
Third-order residual stresses can occur during the welding process, especially at high temperatures. They affect the mechanical strength of the weld and can lead to cracks or distortions. Excessively high stress can also change the microstructure and reduce the toughness of the material.
Workshop Practice & Action Guidelines
To minimize third-order residual stresses, careful pretreatment of the base metal is important. This includes proper cleaning and removal of contaminants or corrosion. In severe cases, mechanical working or a special treatment with a stress-relieving agent may be required. During welding, temperature control and optimized cooling rates are essential to stabilize the microstructure and avoid the formation of residual stresses.