Welding flux
Welding flux is a granular mineral mixture used in submerged arc welding as a cover that melts. It protects the molten pool from the atmosphere, deoxidizes the metal, and shapes the weld bead.
Physical-Chemical Action Mechanism
Welding flux is a blend of mineral substances like silicon dioxide, calcium silicate, and magnesium silicate. It melts under the heat of the weld pool and forms a dense layer on the metal surface. This layer blocks the atmosphere and prevents oxygen from reaching the metal, which would otherwise cause porosity.
Metallurgical Relevance & Risks in Welding
Proper application of welding flux is critical for a high-quality weld. If the flux isn't melted correctly or too little is used, you get incomplete deoxidation and porosity. Too much flux forms a thick layer that hides the metal, restricting gas escape, which also leads to porosity.
Workshop Practice & Action Steps
For optimal use:
• Use the right amount of flux (about 0.5 to 1 g per cm²).
• Make sure the flux is fully melted before you start welding.
• Avoid overdoing it or leaving the flux partially unmelted.