Chemical mix that protects the molten pool, removes oxides and forms slag. It appears as the coating on stick electrodes, the core of flux-cored wire, the granular blanket in submerged arc, and the paste or powder used in brazing and soldering, where it dissolves oxide films so the filler can wet the metal. Most fluxes absorb moisture, which brings porosity and hydrogen cracking, so storage matters.
Sub arc flux sat out in the rain overnight, scrap it, we're not rebaking that.
Also heard as
- flux coating
- brazing flux
- submerged arc flux
Related terms
Slag
The glassy crust that forms on top of a stick, flux-cored or submerged arc weld and is chipped off.
SAW
Submerged arc welding: an arc buried under a blanket of granular flux, used for long, heavy welds.
SMAW
Shielded metal arc welding: arc welding with a flux-coated consumable electrode, known in the shop as stick.
Brazing
Joining metals with a filler melting above 450 °C but below the base metals, drawn in by capillary action.
Wetting
Molten filler spreading across a clean surface and bonding to it, needed for a sound braze or solder.