862 Modern Welding Annealing: Softening metals by heat treatment. Anode: Positive terminal of an electrical circuit. Arc: Flow of electricity through a gaseous space or air gap. Arc blow: Wandering of an electric arc from its normal path because of magnetic forces. Arc cutting: Making a cut in metal using the energy of an electric arc. Arc fl ame: The part of a welding arc that consists of neutral gases that appear to be pale red. Arc gouging: Arc cutting process used to cut a groove in a surface. Arc length: The distance from the welding electrode to the weld pool surface. Arc spraying (ASP): Process using the heat of the arc and a compressed gas to atomize and propel a coating material onto the base material. Arc stud welding (SW): An arc welding process that uses an arc between a stud or similar part and the workpiece, with the application of pressure after the stud and work- piece are suffi ciently heated. Arc voltage: Electrical potential (pressure or voltage) across the arc. Arc welding: A group of welding processes using the heat of an electric arc to melt and weld metal. Arc welding may be done with or without fi ller metal. Argon: Inert, relatively heavy gaseous element used as a shielding gas in welding. Argon-hydrogen mixtures: Shielding gas mixtures used for increased welding speeds during gas tungsten arc welding of stainless steel, nickel-copper, and nickel- based alloys. Armature coil winding: A wire coiled around an arm of a dc generator armature. Each end of the wire is connected to a commutator. Arrow: Part of a welding symbol that always touches the line that represents the welded joint. Arrow side: On the drawing of a welded part, the side of the metal which the arrow touches. Articulated robot: A robot with parts that rotate around various axes. By rotating different joints, the robot can reach virtually any point in a spherical zone surrounding it. Assembly drawing: A drawing that shows a product completely assembled, with all subassemblies and parts. Atom: Smallest whole part of an element. Its nucleus is made up of protons and neutrons. Austenite: High-temperature form of steel. It has a face- centered cubic structure. Austenitic stainless steels: Steels that contain 16% to 30% chromium, 3% to 37% nickel, 2% manganese, and small amounts of silicon, phosphorous, sulfur, and other elements. Automatic cutting: Cutting process that is completely controlled and does not require adjustment once initi- ated. The controller or computer is programmed with the path and speed of the torch or torches. Automatic GTAW system: A system that uses feedback signals to adjust the GTAW process to produce a high- quality weld. Automatic mode: Mode of operation in which a robotic system will perform a program exactly and the program can be repeated over and over. Automatic welding: Welding with equipment that needs minimal monitoring and no manual adjustments during the process. Axis of a weld: An imaginary line through the center of the weld metal from the beginning to the end of the weld. B Backfi re: Short “pop” of the torch fl ame followed by extin- guishing of the fl ame or continued burning of the gases. Background current: Current level that is high enough to maintain the arc but not enough to continue to melt the base metal. Background gas: A gas mixture used to force water out of an underwater chamber and keep oxygen at a safe level. Backhand welding: Welding technique in which the tip of the electrode or torch is pointed away from the direction of travel. Backing: Material that is placed on the root side of a weld to aid in the control of penetration. Backing gas: Shielding gas applied to the root side of a weld. Backing ring: A metal ring placed inside a pipe before butt welding. The backing ring ensures complete weld pene- tration and a smooth inside surface. Backing tape: Fiberglass or ceramic material on an adhe- sive tape. The tape is applied to the root side of a weld to help control the depth of root penetration. Backing weld symbol: A symbol that indicates an addi- tional weld should be made on the root side of the joint to ensure 100% penetration. Backstep method: Starting the fi rst segment of a weld away from the beginning of the joint, then performing a number of short welds, welding each section back toward the previous section. Back view: A view that is possible on an orthographic drawing, but very seldom used. Also referred to as Rear view. Backward arc blow: As the magnetic fl ux intensifi es ahead of the electrode, the arc and molten metal are blown back toward the beginning of the weld. Backward welding: See Backhand welding. Balanced wave: Waveform that results when the same amount of current fl ows during both halves of the ac cycle. Base metal: Metal to be welded, cut, or brazed. Basic oxygen furnace: Furnace that uses oxygen to burn off the carbon and impurities in molten metal to produce steel. Bauxite: Ore from which aluminum is obtained. It consists mostly of hydrated alumina (Al 2 O 2 3H 2 O). Bead: The appearance of the fi nished weld. Also, the metal added in welding. Bell: A chamber that is used to transport divers to and from the surface to the depth where underwater welding will take place.