870 Modern Welding Forward arc blow: Magnetic fi eld forces the molten fi ller metal to blow inward from the end of the weld joint toward the center of the work. Fractional drill sets: Drill sets that increase in size in steps of 1/64″. Fracture test: Identifi cation test that involves breaking a portion of metal in two and examining the grain size and color. Free bend test: Bending a weld specimen without using a fi xture or guide. Free carbon: In steel or cast iron, the part of the total carbon content that is present in the form of graphite or temper carbon. Freehand cutting: Cutting performed without the use of a guide. Friction: Rubbing of two materials against one another. The rubbing action develops heat. Friction stir welding (FSW): A solid-state welding process in which a rotating shouldered tool with a probe or pin moves along a joint, creating heat through friction and pressure. The base metal is plasticized and stirred together. The metal is not melted. Friction welding (FRW): Welding process in which the welding heat is generated by revolving one part against another part, under very heavy pressure to create friction. Front view: The view on a working drawing that shows the greatest amount of detail about an object’s shape and size. Full scale: Drawn at actual size. Full-wave rectifi ed single-phase ac: Alternating current in which the reverse half of the cycle is made to travel the same direction as the other half of the wave. It produces pulsating direct current with no interval between pulses. Full-wave rectifi ed three-phase ac: Conversion of alter- nating current by a rectifi er in which there is little pulsa- tion in the resulting direct current. Fully active (RA) fl uxes: Commonly used soldering fl ux that is the most active and cleans the best. Fumes: Particles suspended in air often produced by high heat. Furnace: An enclosed structure that produces heat by air- fuel gas, by electrical induction, or by electrical resis- tance units. Fuse plugs: Plugs threaded into the base of a gas cylinder. If the cylinder is subjected to a high temperature, the plugs melt and allow the gas to escape before enough pressure builds up to burst the cylinder. Fusion: Intimate mixing or combining of molten metals. Fusion face: The surface of the base metal that is melted during welding. Fusion welding: Any type of welding that uses fusion as part of the process. G Galvanic corrosion: Corrosion caused by a small elec- trical fl ow that is created under certain conditions when dissimilar metals are in contact. Galvanizing: A process that involves coating iron or steel with zinc. Gamma rays: Electromagnetic radiation given off by the nucleus of an atom. Gamma rays always accompany fi ssion. Gantry: A light, rigid rail and all its mechanisms. Torches are mounted on a gantry for automatic cutting operations. Gas: State of matter that consists of particles with neither a defi nite volume nor a defi nite shape. Gas holes: Holes created by gas escaping from molten metal. Gas lens: A device used in a GTAW nozzle to reduce turbu- lence in the shielding gas fl ow. Gas metal arc welding (GMAW): Arc welding using a contin- uously fed consumable electrode and a shielding gas. Some- times incorrectly called MIG welding. Gas pockets: Cavities in weld metal caused by entrapped gas. Gas supplies: The source of gases used in a welding operation. Gas-shielded fl ux cored arc welding (FCAW-G): FCAW method in which a shielding gas is used in addition to the vaporizing fl ux in the electrode core. Gas tungsten arc welding (GTAW): Arc welding using a tungsten electrode and a shielding gas. The fi ller metal is added using a welding rod. Sometimes incorrectly called TIG welding. Gauss: Unit used to measure magnetic fl ux density or induc- tion. One gauss is one line of fl ux per square centimeter. Generator: Device that generates electricity or produces some substance for example, an electric generator or an acetylene generator. Glancing: Tangential, or nearly parallel to. GMAW: See Gas metal arc welding. Gouging: Cutting a groove in the surface of a metal using an oxyfuel gas or arc cutting process. Grain-coarsened region: Region of the heat-affected zone that is next to the weld zone. Grain-refi ned region: Region of the heat-affected zone that is next to the unaffected base metal. After this area is heated to just above the A3 critical temperature, new refi ned grains are formed. Grain size: The size of the individual crystalline particles that make up a metal. Graphitization: Forming of graphite in iron or steel either during solidifi cation or later during heat treatment. Gray cast iron: An iron casting that has been cooled slowly, allowing some of the carbon to separate, forming free graphite (carbon) fl akes. These carbon fl akes are present throughout the microstructure. Groove angle: Part of a groove joint that is the total angle formed between the groove face on one piece and the groove face on the other piece. Groove face: Part of a groove joint that is the surface formed on the edge of the base metal after it has been machined or fl ame cut. Groove joint: A joint that has one or both edges cut or machined to form a bevel, V, U, or J groove. This prepara- tion allows the weld to be made into the bottom of the joint.