Undercut defect
Undercut is a groove at the weld edge, caused by too high energy density or incorrect torch guidance. It weakens the load-bearing cross-section and can act as a pronounced notch area.
Physical-Chemical Mechanism of Action
Undercut occurs when the torch is too strong or not properly aligned. This leads to too high energy density at the weld edge and melting of the metal. The resulting material behaves like a notch and can break the base material under pressure.
Metallurgical Relevance & Welding Risks
Undercut weakens the load-bearing cross-section of the weld, leading to increased stress concentration and potential cracks. It can also alter the microstructure and affect the toughness of the material. In extreme cases, it can cause total failure of the weld.
Workshop Practice & Instructions
To avoid undercut, pay attention to correct torch guidance and ensure that the energy density at the weld edge is not too high. Use an appropriate shielding gas nozzle at the weld edge and regularly check torch settings. In case of suspected undercut, the weld should be inspected immediately and re-welded if necessary.