Flux-cored arc welding, also known as FCAW or FCA, is a semi-automatic or automatic arc welding technique. Flux-cored arc welding requires the use of a tubular electrode which contains a flux to be continuously fed using a constant voltage of constant current welding power supply. On occasion the process requires the use of an external shielding gas, but it is not required all the time because the flux often creates the required protection from contaminates in the atmosphere. This welding process can most commonly be found in construction due to its high welding speed and portability.
The process of flux-cored welding was first developed in the 1950’s as a substitute for shielded metal arc welding. The benefits of using flux-cored welding over shielded metal arc welding is that the stick electrodes used in shielded metal arc welding are unnecessary which makes it easier to use.
One of the fluxed-cored arc welding processes requires no shielding gas to be used while the welding is performed. This is due to the fact that the flux core in the tubular consumable electrode produces its own shielding gas because of the different ingredients that are contained in the electrode. When these ingredients are exposed to the high temperatures produced by welding, they produce a shielding gas that protects the arc. This type of flux-cored welding is favored because of its portability and it produces good penetration into the base metal. This method is also a favorite for welders who have to perform welds outdoors in windy conditions because the process is not interrupted by wind.
Some of the disadvantages of this type of flux-cored arc welding are that this process of welding produces excessive, noxious smoke which makes it difficult for the welder to see the weld pool; it has also been known to produce welds with inferior mechanical properties and the slag can be difficult and time consuming when it needs to removed.
Another type of flux-cored welding requires the use of a shielding gas which must be supplied by an external supply. This flux-cored welding process is known as dual shield welding. This welding process was designed for use in welding structural steels. Since this method uses a combination of a flux-cored electrode and an external shielding gas it could be considered a combination of GMAW and flux-cored arc welding. This welding process is preferred when thicker and out of position metals need to be welded. The slag that is created using this welding technique is much easier to remove than the slag created using the other method of flux-cored welding. The primary advantages of this welding process are that it produces better and more consistent welds when performed in a closed shop. These welds also have fewer defects than the SMAW or GMAW welding processes. It also allows for a higher production rate because the welder does not need to stop to attach a new electrode like they do when the SMAW process is being used. A disadvantage to this method of welding is that it cannot be performed in windy conditions due to the loss of the shielding gas. If it is attempted in this type of weather condition the weld produced will show visible porosity on the surface of the weld.
The flux-cored arc welding process can be used on many different types of metals and alloys such as, stainless steels, high nickel alloys, mild and low alloy steels and some wear facing surfacing alloys. It can also be an all position process and requires less preparation and cleaning of the metals being used. There are many different ways in which this process can be used; it should be a skill that is learned by all welders.