Root Concavity
Incomplete root fusion is an incomplete weld root formation on the back side of the part, caused by too little fill or wrong root penetration. This leads to a weak joint and increases the risk of cracking.
Physical-Chemical Action Mechanism
The weld root is formed by depositing metal into the joint. In case of lack of root fusion, part of the base material remains unwelded because the deposition was too low or the root penetration was incorrect.
Metallurgical Relevance & Risks in Welding
Lack of root fusion leads to a missing bond between the weld metal and the base material. This increases the risk of cracks, especially under mechanical load. The effective thickness is reduced, which affects the overall integrity of the joint.
Workshop Practice & Action Instructions
To avoid lack of root fusion, make sure the weld deposit is sufficient and root penetration is correct. Regularly check the weld for complete root fusion. If lack of root fusion is suspected, carry out a thorough inspection and correct the deposit or penetration if necessary.