Oxidic Line Segregation
Oxide stringers segregation is a linear accumulation of oxygen compounds in the weld metal that did not float out sufficiently during welding. This results in fine, sharp lines in the structure that impair mechanical properties.
Physico-chemical mechanism of action
Oxide banding occurs due to insufficient deoxidation in the weld pool. Oxygen remains in the liquid and forms fine crystal seams that solidify during cooling.
Metallurgical relevance & risks in welding
These banding can impair mechanical properties such as toughness and hardness. They lead to increased susceptibility to cracks and wear, especially under high loads. Furthermore, they can reduce the weld quality and make the microstructure uneven.
Workshop practice & instructions
To avoid oxide banding, it is crucial to carry out careful deoxidation. This can be achieved by using deoxidizers such as silicon or potassium fluoride. The weld pool temperature should be set so that oxygen is released and floats up. Continuous air removal during the welding process is also important. For heavily loaded applications, additional measures such as an increased tempering temperature or a special microstructure should be considered.