Macroscopic lack of fusion
A macroscopic lack of fusion is a large area where the weld metal and base metal aren't metallurgically bonded, visible in a polished and etched cross-section.
Physical-Chemical Mechanism of Action
A macroscopic lack of fusion occurs when there is a missing or incomplete metallurgical bond between the weld metal and the base material. This can be caused by too low welding temperature, too short dwell time, or insufficient pressure on the weld.
Metallurgical Relevance & Risks in Welding
A macroscopic lack of fusion leads to a weak bond between the weld metal and the base material. This can cause cracks, fracture, or failure of the weld, especially under load. Metallographic examination reveals these missing bonds as clear gaps or incomplete structures.
Workshop Practice & Action Instructions
To avoid macroscopic lack of fusion, it is important to set the welding temperature and dwell time correctly. Adequate pressure on the weld is also crucial. If suspected, a metallographic examination should be performed to verify the quality of the bond.