Introduction to Flux Cored Wires

Posted by raveena pawar on September 12th, 2017

Flux-cored arc welding (FCAW) wires are certainly an integral part of the welding process. They aren’t new in the industry but understanding them can be confusing in absence of the right data. A welder needs to be aware of the various applications of flux core wires and with adequate knowledge of the, someone can confidently use them for various welding applications. Flux-cored wires have been available in two main versions: gas-shielded and self-shielded. Flux core wires have been in the welding industry from the 1950s. Both types are made of an outer sheath and are filled with flux from the inside, a compound which is a mixture of alloys, which are necessary to protect the weld from unwanted substances.

Application

FCAW needs electricity, filler metal, and some way to protect the molten metal from the atmosphere. The flux-cored method uses a wire that contains an inner core made of materials that produce fluxing agents and gases. The flux wires generate the protective gas, which makes these wires highly portable and ideal for outdoor welding applications across all industries, such as bridge construction, structural steel, shipbuilding. Common applications for gas-shielded flux-cored wires include general fabrication, pressure vessels, petrochemical piping, and heavy-equipment manufacturing & many other industries. Welding ticker materials become easier with gas shielded flux wires and also for welding out of position applications. Removal of slag materials becomes easier with flux cored wires. FCAW requires a continuously-fed consumable tubular electrode containing a flux and a constant-voltage or, less commonly, a constant-current welding power supply. Flux-cored wires also are available for hardsurfacing new parts to protect them from impact and abrasion and for rebuilding old or worn-out parts. Note that hardsurfacing wires do not have a classification according to the American Welding Society (AWS), but all other gas- and self-shielded flux-cored wires do.

Advantages & Disadvantages

Flux Cored wires have advantages & disadvantages like any other processes. Advantages of both include higher deposition rates than solid wire or stick electrode, nice weld bead appearance, and the ability to weld thick materials.

Flux-cored wires also provide excellent mechanical properties, like high-strength welds and strong impact values, and can be alloyed to match different base materials. These wires tend to be more tolerant of dirt and mill scale and can weld through such contaminants with less pre-cleaning than other types of welding wires or stick electrodes. Note, however, that pre-cleaning is always recommended as a best practice in any welding application. And, finally, flux-cored wires are relatively forgiving, meaning that they generally do not require operators to be as skilled or well-trained as those who weld with other types of filler metals.

The primary disadvantage of flux-cored wires is the post weld cleaning that is required. Both gas-shielded and self-shielded wires produce slag, which must be removed by chipping and/or wire brushing between weld passes or after the final pass is completed. In some cases, these wires also can be more expensive per pound than solid wires.

Myths about Flux Cored Welding

Flux Cored wires are essentially very useful for most welding applications cross various industries. But there are multiple myths associated with flux cored wires, which needs to be busted in the meanwhile. Surprisingly the myths around flux cored wires obstruct companies from considering it a feasible option for their welding requirements.

Let us look at 4 commonly believed myths:

Myth #1 Gas-shielded flux-cored wires more expensive as compared to solid wires.

Truth being he myth: Although gas-shielded flux-cored wire costs more than solid wire, the productivity provided by both the above-mentioned products are nearly the same just a marginal increase in its cost. The slag system of flux-cored wires allows them to be welded at higher electrical current than solid wire without the puddle becoming too fluid or semi solid.

The benefits of gas-shield flux-cored wires over solid wire are further divided in vertical applications. This increases deposition rates of the fluid and allows welding operators to use larger diameter wires than would be possible with solid wire.

Myth #2: flux-cored wires are not apt for outdoor applications.

The truth behind the myth: Yes, a wind screen is extremely important if there is a breeze over 8 km/hr, but that shouldn’t negate the fact that gas-shielded flux-cored wires can provide potential improvements over both flux cored wire and stick welding in certain outdoor applications across various industries. For pipelines, structural steel erection, heavy equipment repair, and a number of other outdoor applications in other work areas, the increased deposition rates of gas-shielded flux-cored wire can result in higher total productivity than self-shielded wire, offsetting the extra time & effort it takes to set up the wind screen.

Myth #3: Flux-cored wire doesn’t benefit from pulse welding.

The truth behind the myth: Most of the flux-cored wires do not show improvised welding performance with pulsed welding. However, the small diameter of wires are not only able to be used with a pulsed welding program, they show definite improvement in spatter reduction.

It is important to do pulsed welding with these wires, however, to use a smaller diameter wire — generally 1.6 mm or less. Also, because of the faster cooling pulsed welding generally results in shallow penetration in the wires than non-pulsed welding, so care should be taken to ensure the weld meets the penetration requirements of the welding application used.

Conclusion:

Before choosing either a gas-shielded or self-shielded flux-cored wire for an application, consider some of this basic information. A clearer understanding of the range and capabilities of this class of wires, however, reveals that they can offer the best combination of efficiency and welder appeal for many industrial welding environments.

In case of any doubts, kindly remember that welding distributors and filler metal manufacturers always are reliable & well-known resources for helping make an informed decision about flux cored wire or any other part of the welding process. The weld qualities and productivity improvements offered by gas shielded flux-cored wires are often overlooked as a result of commonly held myths about their suitability for a variety of applications.