FAQ
Self Shielded vs Gas
Shielded Flux Cored
Electrodes
Q: Why does one use a shielding gas when using a flux-cored wire such as Outershield®
71M? What are the advantages? I have only welded with an Innershield® wire, which did
not use any shielding gas.
A: I would like to answer your question as a general discussion of flux-cored welding. The American
Welding Society (AWS) classifies all tubular electrodes having a flux on the inside as "flux-cored" wires,
and calls it the Flux Cored Arc Welding (FCAW) process. All flux-cored wires have some similar
characteristics. These include forming a protective slag over the weld, use a drag angle technique, have the
ability to weld out-of-position or flat and horizontal only at higher deposition rates (depending on type of
wire), ability to handle contaminants on the plate, etc. However, there are two fundamentally different types
of flux-cored wires. One type is self-shielded and the other type is gas-shielded. These two types are often
subcategorized as the FCAW-S process (self-shielded, flux-cored) and FCAW-G process (gas-shielded,
flux-cored).
Self-shielded, flux-cored wires, commonly referred to as Innershield® wires, are often described as "a stick
electrode that is inside out". Just like covered or stick electrodes, they rely solely on their slag system and
the gases produced from chemical reactions in the arc to protect the molten metal from the atmosphere (see
Figure 1). The flux ingredients in the core perform multiple functions, which include: 1) They deoxidize
and denitrify the molten metal. 2) Forms a protective slag, which also shapes the bead and can hold molten
metal out-of-position. 3) Adds alloying elements to the weld metal to produce desired mechanical
properties. 4) Affects welding characteristics (i.e. deep penetration characteristics and high deposition
rates).
You can think of the FCAW-S process as a productivity extension of stick (i.e., manual) welding, providing
much higher deposition rate capabilities with a semi-automatic process for almost all the same applications