Lack of penetration
Incomplete fusion defects occur when the welding heat does not fully penetrate the entire root cross-section. This leads to insufficient weld thickness and increases the risk of cracks.
Physical-Chemical Mechanism of Action
The welding heat must penetrate the entire root cross-section to create a sound joint. If the heat does not fully penetrate, part of the material remains unmelted, resulting in a thin weld.
Metallurgical Relevance & Risks in Welding
Incomplete fusion defects can lead to cracks and distortion in the component. The parts are then unsafe and can fail under load. Additionally, the unmelted area may be prone to corrosion.
Workshop Practice & Instructions
To avoid incomplete fusion defects, the welding heat must be high enough and the heat duration long enough. Regularly check welding parameters and ensure correct welding direction. If necessary, use additives such as deoxidizers or filler material to assist the fusion process.