electrode to which a covering sufficient to provide a slag layer on the weld metal has been applied. The covering may contain materials providing such functions as shielding from the atmosphere, deoxidation, and arc stabilization, and can serve as a source of metallic additions

to the weld. See SHIELDED METAL ARC WELDING, Covered Electrodes.

The core of the covered electrode consists of either a solid metal rod of drawn or cast material or one fabricated by encasing metal powders in a metallic sheath. The core rod conducts the electric current to the arc and provides filler metal for the joint.

The electrode covering consists of metal and alloy powders, pulverized minerals, and organic materials such as cellulose and silicate binders. The primary functions of the electrode covering are to provide arc stability and to shield the molten metal from the atmosphere with gases created as the coating decomposes from the heat of the arc. Other characteristics contributed by the electrode covering include alloying the weld metal, producing slags to protect and shape the weld pool and providing a dam to help support weld metal in vertical joints.

The shielding medium and the ingredients in the covering and the core wire control the mechanical properties, chemical composition, and metallurgical structure of the weld metal, as well as the arc characteristics of the electrode. The composition of the electrode covering varies according to the type of electrode.

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