Lack of side wall fusion
When lack of fusion occurs at the weld toe due to incomplete melting, it's called a lack of sidewall fusion defect. It's caused by wrong torch angle, too low current, or heavy oxide layers. This leads to poor bonding of the weld bead and can cause cracks and distortion.
Physical-Chemical Mechanism of Action
Incomplete fusion at the weld flank occurs when the torch is not correctly aligned to the workpiece or the current is too low. This prevents complete melting at the flanks of the weld. Heavy oxide layers can also hinder fusion, as they act as a barrier and prevent the metal from being reached.
Metallurgical Relevance & Welding Risks
This defect leads to incompletely bonded weld flanks. The lack of fusion of the weld bead can lead to cracks and distortion in the weld. Additionally, it can result in reduced toughness and durability of the weld, as the metal structure is not optimally bonded.
Workshop Practice & Instructions
To avoid incomplete fusion at the weld flank, ensure correct torch handling. Make sure the torch is perpendicular to the workpiece and the distance to the metal is properly set. Use sufficient current for the chosen material and remove heavy oxide layers before welding by mechanical or chemical surface treatment. Regularly check the torch and current to ensure no incomplete fusion occurs.