Posted by Robert Hernandez on Sep 19th 2026
| Term | Definition |
|---|---|
| Face bend | A test performed by bending a weld sample with the face of the weld on the outside of the bend. |
| Face of weld | The exposed surface of the weld. |
| Face reinforcement | The distance from the top of the weld face to the surface of the base metal. |
| Fahrenheit | A temperature scale used in most English-speaking countries where 32 degrees is the temperature at which water freezes and 212 degrees is the temperature at which it boils, at sea level. |
| Fatigue | A condition in which repeated stress below the tensile strength of a material will cause the material to crack. |
| Feed rate | The speed, in a unit of time, at which an electrode or filler metal rod is fed into the arc crater. |
| Ferrous metals | Those metals or alloys of which the principal base or constituent is iron. |
| Field weld symbol | A symbol added to the basic AWS welding symbol to indicate that a weld is to be made at the job site (in the field), rather than in a fabricating shop. |
| Filler metal | Material to be added in making a weld. |
| Filler passes | The intermediate passes used to fill the joint in a multiple-pass weld. |
| Filler rod | Same as welding rod. |
| Fillet | A radius of weld metal in the interval vertex, or corner, of the angle formed by two pieces of metal, giving the joint additional strength. |
| Fillet weld | Metal fused into a corner formed by two pieces of metal whose welded surfaces are approximately 90 degrees to each other. |
| Fillet weld size | The length of the legs of the triangle inscribed into the cross section of a completed fillet weld. |
| Filter lenses or plates | The lenses in welding goggles and helmets with optical properties that protect the welder’s eyes from infrared, ultraviolet, and visible radiation. |
| Fire watch | A safety practice in which a person is designated to observe a welding operation to prevent fires started by stray sparks or heat from welding activities. |
| Fitting | The threaded connectors on the ends of the water and gas hoses, used to join the hoses to the torch and regulators or adapters. |
| Fixture | A device used to hold a weldment in proper alignment for welding. |
| Flanged edge joint | A joint in two pieces of metal formed by flanging the edges at 90 degrees to the plates and joining with an edge weld. |
| Flared | Curved outward. |
| Flash | Arc flash — the impact of electric arc rays against the human eye. Also, the surplus metal thrown out at the seam of a resistance weld. |
| Flash goggles | Goggles worn under helmets by arc welders to protect their eyes from arc flashes from the rear. |
| Flat bead | A relatively flat bead contour used when the bead is to be ground or machined flat. |
| Flat position | Welding done with the weld axis and base metal surface nearly horizontal. |
| Flaw | A discontinuity in a weld that is larger than the acceptable limit. |
| Fixed automation | Electronically controlled welding system for simple welds (straight or circular). |
| Flexible automation | Robotically controlled welding system for complex shapes requiring torch angle manipulation. |
| Flowability | The ability of a molten filler metal to flow or spread over a metal surface. |
| Flow meter | A device that controls the amount of gas that goes to the welding torch. |
| Flow rate | The volume of a liquid or gas flowing through a hose or torch, usually measured in cubic feet per hour (cfh) or liters per minute (Lpm). |
| Fluorescent dye | A dye that gives off or reflects light when exposed to short wave radiation. |
| Fluorescent penetrant | A penetrating dye fluid used in a non-destructive test of weld integrity to which fluorescent dye has been added to improve the visibility of any discontinuities in a weld. |
| Flux | A chemical compound or mixture in powdered, paste, or liquid form. Its essential function is to combine with or otherwise render harmless those products of the welding operation which would reduce the physical properties of the deposited metal, or make the welding operation difficult or impossible. |
| Flux Cored Arc Welding (FCAW) |
This process melts and joins metals utilizing an arc which heats the metals with a continuous, consumable electrode wire. |
| Flux-cored electrode | A hollow metal electrode filled with a flux material, usually used in FCAW or ESW. |
| Foot pedal | A foot-operated rheostat used for remote control of the output of an arc welding machine, typically a TIG (GTAW) machine. |
| Force gauge | A gauge used to measure the applied force, such as the pressure being exerted by electrodes in resistance spot welding. |
| Forehand welding | That method of welding in which the torch and rod are disposed so that the arc points ahead in the direction of welding and the rod precedes the torch. |
| Forge welding | (FOW) A weld made by heating the parts in a forge, then applying pressure or striking blows with enough force to make them fuse together. |
| Forward arc blow | Arc blow that occurs at the beginning of the joint as the magnetic field tries to stay in the metal. This causes the filler metal to blow toward the center of the joint. |
| Free bend test | Bending a test specimen, usually in a vise, without using a fixture or guide. |
| Freeze | Refers to a welding rod or electrode that becomes stuck in the weld pool. |
| Friction welding | (FRW) A welding process in which frictional heat is created by revolving one part against another under very heavy pressure. |
| Fuel gases | Gases usually used with oxygen for heating such as acetylene, natural gas, propane and other synthetic fuels and hydrocarbons. |
| Full anneal | The application of the heat treating (annealing) process to the full thickness of the workpiece. |
| Fuse | A device designed to prevent current flow in an electrical circuit if the amperage becomes too high. |
| Fuse plug | A safety device employed on compressed gas cylinders consisting of a low melting point alloy, designed to relieve excessive internal pressure due to heat by melting at a predetermined temperature. |
| Fusion | In terms of welding, it is the melting and flowing together of metals. |
| Fusion welding | Any type of welding that uses fusion as part of the process. |
