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Welder’s Handbook
Flashback – When gases “flashback” the flame regresses from outside (off of) the tip in use into the torch body itself. That flame will head to the point where the gases are mixed. The flame will continue to burn at that mixing point as long as fuel and oxygen are present and allowed to flow. Virtually all torches in flashback mode will “whistle, howl, screech,” etc. If the operator does NOTHING, the torch will begin to destroy itself in a matter of seconds, with the flame burning through the torch at some weak point. In addition, if unchecked, the flame may continue to migrate upstream seeking fuel/oxygen to continue burning. Ultimately, that “flame front” could end up at the gas source itself destroying parts and pieces along the way. Even if the fuel gas is shut off, with oxygen still flowing, the “guts” of the torch can continue to burn. Flat Welding Position – The welding position used to weld from the upper side of the joint at a point where the weld axis is approximately horizontal, and the weld face lies in an approximately horizontal plane. Flux – In arc welding, fluxes are formulations that, when subjected to the arc, act as a cleaning agent by dissolving oxides, releasing trapped gases and slag and generally cleaning the weld metal by floating the impurities to the surface where they solidify in the slag covering. The flux also serves to reduce spatter and contributes to weld bead shape. The flux may be the coating on the electrode, inside the electrode as in flux cored types, or in a granular form as used in submerged arc welding. Flux Cored Electrodes – A composite tubular filler metal electrode consisting of a metal sheath and a core of various powdered materials, producing an extensive slag cover on the face of a weld bead. External shielding may be required. Flux Voids – Section of a flux cored electrode which contains no flux. Voids can cause serious problems, especially in low alloy types.
Full Annealing – Heating of steels or iron alloys to above their critical temperature range, soaking at the annealing temperature until they are transformed to a uniform austenitic structure, followed by cooling at a predetermined rate, depending upon the type of alloy and structure required; in general the cooling rate is relatively slow. Fumes – Airborne solid particulate matter generated by the welding or cutting process. Fume particles are usually sub- micron in size and thus tend to remain airborne and drift with the air currents. Keep welders and workshop staff safe with welding fume extraction systems. Fused Fluxes – Fused fluxes are melted ingredients which have been chilled and ground to a particular particle size. The advantage of this type flux is the low moisture pick-up and improved recycling capabilities.
Fusion – The melting together of filler metal and base metal, or of base metal only, to produce a weld.
Fusion Zone – The area of base metal melted as determined on the cross section of a weld. G Galling – The condition between rubbing surfaces where high spots or protrusions on a surface become friction welded to the mating surface, resulting in spalling and further deterioration. Gas Ions – Shielding gas atoms that, in the presence of an electrical current, lose one or more electrons and therefore, carry a positive electrical charge. The provide a more electrically conductive path for the arc between the electrode and the work piece.
Gas Nozzle – A device at the exit end of the torch or gun that directs shielding gas.
Gas Metal Arc Welding (GMAW) – An arc welding process wherein coalescence is produced by heating with an arc between a continuous filler metal (consumable) electrode and the work. Shielding is obtained entirely from an externally supplied gas, or gas mixture. Some methods of this process are called MIG (Metal Inert Gas) or CO2 welding. MIG welding requires the use of an inert shield gas.
Forging – Deforming into new shape by compressive force.
Forehand Welding – A welding technique in which the welding torch or gun flame is directed away from the finished weld. Friction Stir Welding – A process in which metals are welded together by friction created by a rotating tool which softens but does not melt the metal. No metal is actually cut. Fuel Efficiency – The factor relating to the volume of fuel in cu. ft. needed to duplicate the efficiently of acetylene which is designated as 1.0 cu. ft.
Gas Regulator – A device for controlling the delivery of gas at some substantially constant pressure.
Gas Tungsten Arc Welding (GTAW) – An arc welding process wherein coalescence is produced by heating with an arc between a single tungsten (nonconsumable) electrode and the work. Shielding is obtained from a gas or gas mixture. Pressure may or may not be used and filler metal may or may not be used. (This process is frequently called TIG welding.)
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