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Flux - Flux is applied to metal to prevent oxidation during the joining operations; to reduce surface tension; to promote the flow of the alloy and to facilitate the bonding action between the base metal and the deposited metal. The flux may be in the form of a paste, powder or liquid. Flux should not be used to clean dirty, oxidized, or oily metal. If used for this purpose, its bonding characteristics will be weakened and joint failure result. All foreign matter should be removed by mechanical means (chipping, grinding or wire brushing), or by chemical means (tetrachloride, trisodium phosphate, trichlorethylene, etc.). Heavily greased parts may be subjected to steam jets, followed by mechanical or chemical cleaning. Ferrous Alloys - Metallic alloys which are predominantly iron such as cast iron, wrought iron, steel and stainless steel. Face - The surface of the weld as seen from the side of the joint on which the weld was made. Face Rotation - Can be thought of as an imaginary line from the axis of the weld through the center of the welds face. This face rotation angle along with the axis angle determine the actual welding position. Face rotation is measured in a clockwise direction starting from the 6 o’clock position. A weld with the face rotation at 12 o’clock would have the face rotation at 1800. Ferrous - Refers to a metal that contains primarily iron, such as steel, stainless steel and cast iron. Filler Metal - The metal added when making a welded, brazed, or soldered joint. Fillet Weld - A weld that is used to join base metal surfaces that are approximately 90° to each other, as used on T-joint, corner joint or lap joint. The cross sectional shape of a fillet weld is approximately triangular. Fit-Up - Often used to refer to the manner in which two members are brought together to be welded, such as the actual space or any clearance or alignment between two members to be welded. Proper fit-up is important if a good weld is to be made. Tacking, clamping or fixturing is often done to ensure proper fit-up. Where it applies, base metal must be beveled correctly and consistently. Also, any root openings or joint angles must be consistent for the entire length of a joint. An example of poor fit-up can be too large of a root opening in a V-groove butt weld. Flat Position - When welding is done from the top side of a joint, it is in the flat position if the face of the weld is approximately horizontal. Sometimes referred to as downhand welding. The axis angle can be from 0° – 15° in either direction from a horizontal surface. Face rotation can be from 150° – 210°. Flux Cored Arc Welding (FCAW) - An arc welding process which melts and joins metals by heating them with an arc between a continuous, consumable tubular electrode wire (consumable) and the workpiece. Shielding is obtained from a flux contained within the electrode’s tubular core. Depending upon the type of flux-cored wire, added shielding may or may not be provided from externally supplied gas or gas mixture. Freeze Lines - The lines formed across a weld bead. They are the result of the weld pool freezing. In appearance they sometimes look as if one tiny weld was continuously laid upon another. Frequency - The number of double directional changes made by an alternating current in one second. Usually referred to as “hertz per second” or “cycles per second”. In the , the frequency or directional change of alternating current is usually 60 hertz. Some Advanced Squarewave power sources allow the arc frequency to be adjusted. As arc frequency is increased the arc becomes more directional. Filling Density – The percent ratio of the weight of gas in a container to the weight of water that the container will hold at 60 ?F. Fire Hazard – See “EPA Hazard Categories.” Flammable Gas – (1) A gas that, at ambient temperature and pressure, forms a flammable mixture with air at a concentration of 13% by volume or less; or (2) a gas that, at ambient temperature and pressure, forms a range of flammable mixtures with air wider than 12% by volume regardless of the lower limit. Flammable Limits – The concentration of flammable vapor in air, oxygen, or other oxidant that will propagate flame upon contact when provided with a source of ignition. The lower explosive limit (LEL) is the concentration below which a flame will not propagate; the upper explosive limit (UEL) is the concentration above which a flame will not propagate. A change in temperature or pressure may vary the flammable limits. Flammable Range – The range over which a gas at NTP will form a flammable mixture with air. Flash Point – The lowest temperature at which a flammable liquid will give off enough vapor at or near its surface to form an ignitable mixture with air. Flow Capacity – The maximum flow capability of a control device established at a specific set of conditions. Fluid – Any material or substance that changes shape uniformly in response to an external force imposed upon it. The term applies to liquids, gases and finely divided solids. Freezing Point – The temperature at which a liquid solidifies. It is the temperature at which the liquid and solid states of a substance are in equilibrium at a given pressure (usually atmospheric). For pure substances, it is identical with the melting point of the solid form.
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