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WIRE WELDING Flux Cored Arc Welding (FCAW) Gasshielded .

Gasshielded.

The gas-shielded flux-cored process may be looked upon as a hybrid between self-shielded flux-cored arc welding and gas metal-arc welding. Tubular electrode wire is used as in the self-shielded process, but the ingredients in its core are for fluxing, deoxidizing, scavenging, and sometimes alloying additions, rather than for the generation of protective vapours. In this respect, the process has similarities to the self-shielded flux-cored wire process, and the tubular wires are classified by the AWS along with wires used in the self-shielded process. On the other hand, the process is similar to gas metal-arc welding in as much as a gas is separately applied to act as an arc shield.

The guns and welding heads for semiautomatic and full-automatic welding with the gas-shielded processes are out of necessity more complex than those used in selfshielded flux-cored welding. Space

passages must be included for the flow of gases. If the gun is watercooled, additional space is required. The wire feeder and power source is similar to the equipment used with the self-shielded flux-cored wire process, and gas metal arc welding with only small modifications (wire feed rolls should be knurled). Note that the welding gun should be connected to the positive terminal (+). Although CO2 is generally used as the shielding gas, mixtures of 20% CO2 -80% Argon and 95% Argon - 5% Oxygen, may also be used. The gas-shielded flux-cored process is used for welding mild steel, lowalloy steels and stainless steel. It gives high deposition rates, high deposition efficiencies, and high operating factors. Radiographic quality welds are easily produced, and the weld metal with mild and low-alloy steels has good ductility and toughness. The process is adaptable to a wide variety of joints and gives the capability for all-position welding.

The arc:

Contact Tip

Solidified Slag

Nozzle Flux Core Wire

4.03

Arc Solidified Weld Metal Base Material Gas shielding from cylinder

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