Undercut Depth
Notch depth at the weld toe is the vertical depth of an unintended indentation at the weld transition compared to the original plate surface. It is caused by insufficient or excessive notching, leading to porosity and reduced mechanical properties.
Physico-chemical mechanism of action
The notch depth at the weld toe occurs when the plates are not correctly notched during welding. This can cause uneven stresses and deformations, which manifest as indentations at the weld transition.
Metallurgical relevance & risks when welding
A high notch depth at the weld toe leads to porosity, as uneven stresses draw air bubbles into the weld. This reduces the mechanical properties of the weld, such as strength and toughness, and increases the risk of cracks and hot cracks.
Workshop practice & instructions
To achieve an optimal notch depth at the weld toe, the plates should be correctly notched before welding. This requires a precisely adjusted notching machine with the correct parameters such as notch width and notch depth. A notch depth of 0.5 to 1 mm is generally appropriate. If the notches are too deep or too shallow, the machine should be calibrated to ensure consistent notch quality.