Welding consumables.(electrode equipment)(Illustration)

Welding shops require many types of equipment, including power supplies, guns, torches, wire feeders, flux-handling devices, and accessories such as cables and ground clamps, as well as consumables--filler metals, fluxes, and shielding gases. For brazing, shops employ furnaces and custom-built fixtures.

FILLER METALS, ELECTRODES

Shielded-metal-arc welding (SMAW, `stick')

AWS (American Welding Society) A5 specifications set standards for electrodes for SMAW of carbon, stainless, and low-alloy steels; aluminum, copper, and nickel and their alloys; and weld-surfacing. Designations for covered electrodes carry the prefix `E'. Packaged to AWS specifications, electrodes come in boxes, cans, or other containers, labeled with their AWS specification and trade name, quality-control (heat or lot) number, supplier name, diameter and length, and weight of contents. Specifications require that every electrode be marked for identification with its numeric designation the grip end.

To select a covered SMAW electrode, consider these factors, in approximate order of importance.

1. Mechanical properties of the base material. Tensile strength and yield strength of the weld metal should equal or exceed that of the base material. Ductility and toughness at low temperatures may also be important. High-temperature service requires resistance to creep. Shock loading requires impact resistance. In general, weld metal should match base-material properties.

2. Composition of the base material. For stainless steels, low-alloy steels, nickel and copper alloys, and materials that serve in corrosive atmospheres, chemical composition is important. Consider also the possibility of electrochemical corrosion between base metal and weld metal of different compositions.