Welding Flux: A Shielding Agent between two materials

Published on 16 August 2023

5 min

All that You Need to Know About Welding Flux

The term flux, in the English language, means a continuous flow. In the world of welding, flux denotes a mixture of materials, typically carbonate and silicate. The key use of flux in welding is to protect the weld metal from contamination by atmospheric gases.
The flux ingredients are usually: calcium, calcium carbonate, calcium fluoride, magnesium, potassium and manganese oxides, sodium, silica, and aluminium oxide. The flux ingredients come together to help stabilize the arc and have more control over the mechanical properties.

What are the functions of Welding Flux?

A shielding agent: The welding flux has a lesser density than the weld metal. Therefore, while welding, the welding flux melts and floats around the weld and deposits itself.
Prevents oxidation: The welding flux, upon heating, produces gases that push back the atmospheric gases and prevents oxidation as well as any potential reactions that could occur with nitrogen.
Creates slag for further shielding: The remains of welding flux solidify to create slag, which adds to the protection of the welded area.
Usage as a coating in electrodes: Many forms of arc welding use welding flux, i.e, Shielded Metal Arc Welding (SMAW), Submerged Arc Welding (SAW), and Flux Cored Arc Welding or FCAW.

Use of Flux in Welding Processes

SAW

Submerged Arc Welding or SAW uses welding flux, also commonly known as SAW flux here, to provide the shielding properties mentioned above. SAW flux is usually granular in nature to provide higher deposition rates. The mechanical properties of the weld are also determined by the flux.

The SAW flux also controls the heat in while welding, which helps in concentrating the heat and furthering deeper weld penetration.

SMAW

Shielded Metal Arc Welding or SMAW uses solid core wires for its electrode. The welding flux is coated to the bare electrode by a process called extrusion. The coated electrode aids in arc striking, arc stability, and slag removal apart from the functions of the welding flux.

FCAW

Flux Cored arc Welding, as the name suggests, uses welding flux as a core part of its process. The flux-cored wire used in this welding has flux at its core.
The flux-cored wires are further divided into gas-shielded and self-shielded. These are self-explanatory - the gas-shielded ones require additional shielding against atmospheric gases while welding. Other common subtypes of flux-cored wires include low alloy steel flux.

Flux-cored wire consumables have many benefits wherein they have high deposition rates and can be used in all welding positions. They result in stronger and cleaner welds when compared with other forms of welding. This makes Flux Cored Arc Welding ideal for welding outdoors, in windy conditions, and for welding contaminated materials with scale and rust too!

While there are many types of welding, which type of welding to be used is determined by the scale and nature of the project, the outcome required, and the welding positions suitable.

Never let the materials available be a deciding factor. All your welding materials and welding consumables are available at D&H Sécheron. Among the many welding products that D&H Sécheron has to offer, you can find many types of welding flux in our MAXFLUX range and Flux Cored Arc Welding at our website.

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