Root lack of fusion
Root lack of fusion occurs when the weld is not fully penetrated and the root is not properly fused. This can lead to an open crack on the back side of the joint.
Physicochemical Mechanism of Action
The weld forms by fusion of metal parts under the influence of temperature and stress. If the groove angle is wrong or the current is too low, the metal cannot fully fuse, especially at the root of the weld.
Metallurgical Relevance & Risks in Welding
A root lack of fusion leads to an open crack on the backside of the part. This can cause mechanical loading and cracking, endangering the structure. The parts can no longer be used safely.
Workshop Practice & Procedures
To avoid root lack of fusion:
• Make sure the groove angle is set correctly (usually 30° to 45°).
• Use a sufficiently high current to ensure full penetration.
• Regularly check the weld for completeness and fusion.