A – C
ACETONE: A highly flammable liquid used in welding to dissolve and stabilize acetylene, a type of gas, in cylinders under high pressure.
ACETYLENE: A highly flammable gas made of carbon and hydrogen, often used as a fuel in welding processes.
ACTUAL THROAT: Refers to the THROAT OF FILLET WELD, which is the distance from the root of the weld to the center of its face.
AIR-ACETYLENE: A type of flame used in welding that is produced when acetylene is burned with air instead of oxygen.
AIR-ARC CUTTING: A metal cutting process where the metal is melted by an electric arc.
ALLOY: A mix of two or more elements, including at least one metal, that has metallic properties.
ALTERNATING CURRENT (AC): An electric current that constantly changes its direction.
AMMETER: A tool that measures the amount of electric current in a circuit.
ANNEALING: The process of slowly heating and cooling steel to change its properties, such as making it softer or altering its structure.
ARC BLOW: The bending of an electric arc off its usual path due to magnetic forces.
ARC BRAZING: A type of brazing where heat is obtained from an electric arc.
ARC CUTTING: A metal cutting technique that melts metals using the heat of an electric arc.
ARC LENGTH: The distance between the end of the electrode and the molten metal in welding.
ARC-OXYGEN CUTTING: A process that cuts metals by chemically reacting oxygen with a base metal at high temperatures.
ARC VOLTAGE: The electrical tension across the welding arc.
ARC WELDING: A group of welding techniques that use an electric arc’s heat, sometimes with added metal, to join materials.
AS WELDED: The state of the weld and welded joints right after welding and before any additional treatments.
ATOMIC HYDROGEN WELDING: A welding process that uses an electric arc between two metal electrodes in a hydrogen atmosphere.
AUSTENITE: A non-magnetic form of iron that results from heating steel above a certain temperature, and can absorb a lot of carbon and other elements.
AXIS OF A WELD: A line through the length of a weld, perpendicular to a cross-section at its center of gravity.
BACK FIRE: The momentary burning back of a flame into the tip, followed by a snap or pop, then immediate reappearance or burning out of the flame.
BACK PASS: A pass made to deposit a back weld.
BACK UP: In flash and upset welding, a locator used to transmit all or a portion of the upsetting force to the workpieces.
BACK WELD: A weld deposited at the back of a single groove weld.
BACKHAND WELDING: A welding technique in which the flame is directed towards the completed weld.
BACKING STRIP: A piece of material used to retain molten metal at the root of the weld and/or increase the thermal capacity of the joint so as to prevent excessive warping of the base metal.
BACKING WELD: A weld bead applied to the root of a single groove joint to assure complete root penetration.
BACKSTEP: A sequence in which weld bead increments are deposited in a direction opposite to the direction of progress.
BARE ELECTRODE: An arc welding electrode that has no coating other than that incidental to the drawing of the wire.
BARE METAL-ARC WELDING: An arc welding process in which fusion is obtained by heating with an unshielded arc between a bare or lightly coated electrode and the work. Pressure is not used and filler metal is obtained from the electrode.
BASE METAL: The metal to be welded or cut. In alloys, it is the metal present in the largest proportion.
BEAD WELD: A type of weld composed of one or more string or weave beads deposited on an unbroken surface.
BEADING: See STRING BEAD WELDING and WEAVE BEAD.
BEVEL ANGLE: The angle formed between the prepared edge of a member and a plane perpendicular to the surface of the member.
BLACKSMITH WELDING: See FORGE WELDING.
BLOCK BRAZING: A brazing process in which bonding is produced by the heat obtained from heated blocks applied to the parts to be joined and by a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metal. The filler metal is distributed in the joint by capillary attraction.
BLOCK SEQUENCE: A building up a sequence of continuous multipass welds in which separated lengths of the weld are completely or partially built up before intervening lengths are deposited. See BUILDUP SEQUENCE.
BLOW HOLE: A blowhole is a type of weld defect. It is a gas cavity or bubble that forms inside the solidified weld metal, usually due to gases being trapped during the welding process. This happens when the gas does not escape before the metal solidifies, causing a hole or cavity. Also see GAS POCKET.
BOND: The junction of the welding metal and the base metal.
BOXING: The operation of continuing a fillet weld around a corner of a member as an extension of the principal weld.
BRAZING: A group of welding processes in which a groove, fillet, lap, or flange joint is bonded by using a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metals. Filler metal is distributed in the joint by capillary attraction.
BRAZE WELDING: A method of welding by using a filler metal that liquifies above 450 ºC (842 ºF) and below the solid state of the base metals. Unlike brazing, the filler metal is not distributed in the joint by capillary action in braze welding.
BRIDGING: A welding defect caused by poor penetration. A void at the root of the weld is spanned by weld metal.
BUCKLING: Distortion caused by the heat of a welding process.
BUILDUP SEQUENCE: The order in which the weld beads of a multipass weld are deposited with respect to the cross section of a joint. See BLOCK SEQUENCE.
BUTT JOINT: A joint between two workpieces in such a manner that the weld joining the parts is between the surface planes of both of the pieces joined.
BUTT WELD: A weld in a butt joint.
BUTTER WELD: A weld caused of one or more string or weave beads laid down on an unbroken surface to obtain desired properties or dimensions.
CAPILLARY ATTRACTION: The phenomenon by which adhesion between the molten filler metal and the base metals, together with surface tension of the molten filler metal, causes distribution of the filler metal between the properly fitted surfaces of the joint to be brazed.
CARBIDE PRECIPITATION: A condition occurring in austenitic stainless steel which contains carbon in a supersaturated solid solution. This condition is unstable. Agitation of the steel during welding causes the excess carbon in solution to precipitate. This effect is also called weld decay.
CARBON-ARC CUTTING: A process of cutting metals with the heat of an arc between a carbon electrode and the work.
CARBON-ARC WELDING: A welding process in which fusion is produced by an arc between a carbon electrode and the work. Pressure and/or filler metal and/or shielding may or may not be used.
CARBURIZING FLAME: An oxyacetylene flame in which there is an excess of acetylene. Also called excess acetylene or reducing flame.
CASCADE SEQUENCE: Subsequent beads are stopped short of a previous bead, giving a cascade effect.
CASE HARDENING: A process of surface hardening involving a change in the compsition of the outer layer of an iron base alloy by inward diffusion from a gas or liquid, followed by appropriate thermal treatment. Typical hardening processes are carburizing, cyaniding, carbonitriding, and nitriding.
CHAIN INTERMITTENT FILLET WELDS: Two lines of intermittent fillet welds in a T or lap joint in which the welds in one line are approximately opposite those in the other line.
CHAMFERING: The preparation of a welding contour, other than for a square groove weld, on the edge of a joint member.
COALESCENCE: The uniting or fusing of metals upon heating.
COATED ELECTRODE: An electrode having a flux applied externally by dipping, spraying, painting, or other similar methods. Upon burning, the coat produces a gas which envelopes the arc.
COMMUTORY CONTROLLED WELDING: The making of a number of spot or projection welds in which several electrodes, in simultaneous contact with the work, progressively function under the control of an electrical commutating device.
COMPOSITE ELECTRODE: A filler metal electrode used in arc welding, consisting of more than one metal component combined mechanically. It may or may not include materials that improve the properties of the weld, or stabilize the arc.
COMPOSITE JOINT: A joint in which both a thermal and mechanical process are used to unite the base metal parts.
CONCAVITY: The maximum perpendicular distance from the face of a concave weld to a line joining the weld toes.
CONCURRENT HEATING: Supplemental heat applied to a structure during the course of welding.
CONE: The conical part of a gas flame next to the orifice of the tip.
CONSUMABLE INSERT: Preplaced filler metal which is completely fused into the root of the joint and becomes part of the weld.
CONVEXITY: The maximum perpendicular distance from the face of a convex fillet weld to a line joining the weld toes.
CORNER JOINT: A joint between two members located approximately at right angles to each other in the form of an L.
COVER GLASS: A clear glass used in goggles, hand shields, and helmets to protect the filter glass from spattering material.
COVERED ELECTRODE: A metal electrode with a covering material which stabilizes the arc and improves the properties of the welding metal. The material may be an external wrapping of paper, asbestos, and other materials or a flux covering.
CRACK: A fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement.
CRATER: A depression at the termination of an arc weld.
CRITICAL TEMPERATURE: The transition temperature of a substance from one crystalline form to another.
CURRENT DENSITY: Amperes per square inch of the electrode cross sectional area.
CUTTING TIP: A gas torch tip especially adapted for cutting.
CUTTING TORCH: A device used in gas cutting for controlling the gases used for preheating and the oxygen used for cutting the metal
CYLINDER: A portable cylindrical container used for the storage of a compressed gas.
D – F
DEFECT: A discontinuity or discontinuities which, by nature or accumulated effect (for example, total crack length), render a part or product unable to meet the minimum applicable acceptance standards or specifications. This term designates rejectability.
DEPOSITED METAL: Filler metal that has been added during a welding operation.
DEPOSITION EFFICIENCY: The ratio of the weight of deposited metal to the net weight of electrodes consumed, exclusive of stubs.
DEPTH OF FUSION: The distance from the original surface of the base metal to that point at which fusion ceases in a welding operation.
DIE: In welding, a “die” refers to a tool used in both resistance and forge welding. In resistance welding, it’s shaped to match the workpiece, clamping the parts together while conducting the welding current. In forge welding, a die is used to shape the hot workpiece and apply the necessary pressure.
DIE WELDING: A forge welding process in which fusion is produced by heating in a furnace and applying pressure through dies.
DIP BRAZING: A brazing process in which bonding is produced by heating in a molten chemical or metal bath and by using a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metals. The filler metal is distributed in the joint by capillary attraction. When a metal bath is used, the bath provides the filler metal.
DIRECT CURRENT ELECTRODE NEGATIVE (DCEN): The arrangement of direct current arc welding leads in which the work is the positive pole and the electrode is the negative pole of the welding arc.
DIRECT CURRENT ELECTRODE POSITIVE (DCEP): The arrangement of direct current arc welding leads in which the work is the negative pole and the electrode is the positive pole of the welding arc.
DISCONTINUITY: An interruption of the typical structure of a weldment, such as lack of homogeneity in the mechanical, metallurgical, or physical characteristics of the material or weldment. A discontinuity is not necessarily a defect.
DRAG: The horizontal distance between the point of entrance and the point of exit of a cutting oxygen stream.
DUCTILITY: The property of a metal which allows it to be permanently deformed, in tension, before final rupture. Ductility is commonly evaluated by tensile testing in which the amount of elongation and the reduction of area of the broken specimen, as compared to the original test specimen, are measured and calculated.
DUTY CYCLE: The percentage of time during an arbitrary test period, usually 10 minutes, during which a power supply can be operated at its rated output without overloading.
EDGE JOINT: A joint between the edges of two or more parallel or nearly parallel members.
EDGE PREPARATION: The contour prepared on the edge of a joint member for welding
EFFECTIVE LENGTH OF WELD: The length of weld throughout which the correctly proportioned cross section exits.
ELECTRIC ARC: An electric arc refers to the discharge of electricity across a gap in a circuit. This discharge produces intense heat (up to 6500 degrees Fahrenheit or about 3600 degrees Celsius), which is used to melt the filler material and the parts to be welded. The electric arc is established between the workpiece and an electrode, which can be either consumable or non-consumable, depending on the type of welding process. The electric arc is the heart of many common welding processes, such as Shielded Metal Arc Welding (SMAW), Gas Tungsten Arc Welding (GTAW), and Gas Metal Arc Welding (GMAW).
ELECTRODE: An electrode is a component of the welding apparatus that is used to conduct current through a workpiece to fuse two pieces together. Depending on the process, the electrode can be either consumable or non-consumable. A consumable electrode melts during the welding process to become a part of the weld itself. These are used in processes such as Shielded Metal Arc Welding (SMAW) or Gas Metal Arc Welding (GMAW). A non-consumable electrode, on the other hand, does not melt and become part of the weld. Instead, it is used to direct the current and generate the necessary heat. The most common type of non-consumable electrode is made from tungsten and is used in Tungsten Inert Gas (TIG) welding.
ELECTRODE FORCE: In welding, specifically in resistance welding, electrode force refers to the pressure applied by the electrodes onto the workpieces. It ensures proper electrical contact, controls deformation, aids in heat generation, and assists in forming a strong bond during the welding process. Its optimal value varies based on the materials and the specific welding application.
ELECTRODE HOLDER: A device used for mechanically holding the electrode and conducting its current.
ELECTRODE SKID: The sliding of an electrode along the surface of the work during spot, seam, or projection welding.
EMBOSSMENT: A rise or protrusion from the surface of a metal.
ETCHING: A process of preparing metallic specimens and welds for macrographic or micrographic examination.
FACE REINFORCEMENT: Reinforcement of weld at the side of the joint from which welding was done.
FACE OF WELD: The exposed surface of a weld, made by an arc or gas welding process, on the side from which welding was done.
FAYING SURFACE: That surface of a member that is in contact with another member to which it is joined.
FERRITE: The virtually pure form of iron existing below the lower critical temperature and characterized by a body-centered cubic lattice crystal structure. It is magnetic and has very slight solid solubility for carbon.
FILLER METAL: Metal to be added in making a weld.
FILLET WELD: A weld of approximately triangular cross section, as used in a lap joint, joining two surfaces at approximately right angles to each other.
FILTER GLASS: A colored glass used in goggles, helmets, and shields to exclude harmful light rays.
FLAME CUTTING: see OXYGEN CUTTING.
FLAME GOUGING: See OXYGEN GOUGING.
FLAME HARDENING: A method for hardening a steel surface by heating with a gas flame followed by a rapid quench.
FLAME SOFTENING: A method for softening steel by heating with a gas flame followed by slow cooling.
FLASH: Metal and oxide expelled from a joint made by a resistance welding process.
FLASH WELDING: A resistance welding process in which fusion is produced simultaneously over the entire area of abutting surfaces by the heat obtained from resistance to the flow of current between two surfaces and by the application of pressure after heating is substantially completed. Flashing is accompanied by the expulsion of metal from the joint.
FLASHBACK: The burning of gases within the torch or beyond the torch in the hose, usually with a shrill, hissing sound.
FLAT POSITION: The position in which welding is performed from the upper side of the joint and the face of the weld is approximately horizontal.
FILM BRAZING: A process in which bonding is produced by heating with a molten nonferrous filler metal poured over the joint until the brazing temperature is attained. The filler metal is distributed in the joint by capillary attraction. See BRAZING.
FLOWMETER: Used to regulate gasses used in welding, such as helium and argon.
FLOW WELDING: A process in which fusion is produced by heating with molten filler metal poured over the surfaces to be welded until the welding temperature is attained and the required filler metal has been added. The filler metal is not distributed in the joint by capillary attraction.
FLUX: A cleaning agent used to dissolve oxides, release trapped gases and slag, and to cleanse metals for welding, soldering, and brazing.
FOREHAND WELDING: A gas welding technique in which the flare is directed against the base metal ahead of the completed weld.
FORGE WELDING: A group of welding processes in which fusion is produced by heating in a forge or furnace and applying pressure or blows.
FREE BEND TEST: A method of testing weld specimens without the use of a guide.
FULL FILLET WELD: A fillet weld whose size is equal to the thickness of the thinner member joined.
FURNACE BRAZING: A process in which bonding is produced by the furnace heat and a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metals. The filler metal is distributed in the joint by capillary attraction.
FUSION: A thorough and complete mixing between the two edges of the base metal to be joined or between the base metal and the filler metal added during welding.
FUSION ZONE (FILLER PENETRATION): The area of base metal melted as determined on the cross section of a weld.
G – I
GAS CARBON-ARC WELDING: An arc welding process in which fusion is produced by heating with an electric arc between a carbon electrode and the work. Shielding is obtained from an inert gas such as helium or argon. Pressure and/or filler metal may or may not be used.
GAS METAL-ARC (MIG) WELDING (GMAW): An arc welding process in which fusion is produced by heating with an electric arc between a metal electrode and the work. Shielding is obtained from an inert gas such as helium or argon. Pressure and/or filler metal may or may not be used.
GAS POCKET: A weld cavity caused by the trapping of gases released by the metal when cooling.
GAS TUNGSTEN-ARC WELDING (GTAW): Also known as “TIG welding”, is an arc welding process in which fusion is produced by heating with an electric arc between a tungsten electrode and the work while an inert gas forms around the weld area to prevent oxidation. No flux is used.
GAS WELDING: A process in which the welding heat is obtained from a gas flame.
GLOBULAR TRANSFER: A type of metal transfer in which molten filler metal is transferred across the arc in large droplets.
GMAW: Gas metal arc welding (also known as MIG, flux cored arc welding, spray arc welding and short circuit welding) is used for 70% of welding done today. Offers fast welding speeds, a narrow bead and deep penetration. The process uses continuously fed electrode wire and a shielding gas.
GOGGLES: A device with colored lenses which protect the eyes from harmful radiation during welding and cutting operations.
GROOVE: The opening provided between two members to be joined by a groove weld.
GROOVE ANGLE: The total included angle of the groove between parts to be joined by a groove weld.
GROOVE FACE: That surface of a member included in the groove.
GROOVE RADIUS: The radius of a J or U groove.
GROOVE WELD: A weld made by depositing filler metal in a groove between two members to be joined.
GROUND CONNECTION: The connection of the work lead to the work.
GTAW: Welding using an electric arc and non-consumable tungsten electrode in a water cooled torch. Also called TIG or HELLIARC welding.
GUIDED BEND TEST: A bending test in which the test specimen is bent to a definite shape by means of a jig.
HAMMER WELDING: A forge welding process.
HAND SHIELD: A device used in arc welding to protect the face and neck. It is equipped with a filter glass lens and is designed to be held by hand.
HARD FACING: A particular form of surfacing in which a coating or cladding is applied to a surface for the main purpose of reducing wear or loss of material by abrasion, impact, erosion, galling, and cavitation.
HARD SURFACING: The application of a hard, wear-resistant alloy to the surface of a softer metal.
HARDENING: This term refers to a process used to increase the hardness of metal, typically iron-based alloys, by heating it above a certain critical temperature range and then rapidly cooling or “quenching” it. This process often results in the formation of a structure called martensite, which contributes to the metal’s increased hardness. It’s a technique commonly used in various metalworking and fabrication processes.
HEAT AFFECTED ZONE: That portion of the base metal whose structure or properties have been changed by the heat of welding or cutting.
HEAT TIME: The duration of each current impulse in pulse welding.
HEAT TREATMENT: An operation or combination of operations involving the heating and cooling of a metal or an alloy in the solid state for the purpose of obtaining certain desirable conditions or properties. Heating and cooling for the sole purpose of mechanical working are excluded from the meaning of the definition.
HEATING GATE: The opening in a thermit mold through which the parts to be welded is preheated.
HELMET: A device used in arc welding to protect the face and neck. It is equipped with a filter glass and is designed to be worn on the head.
HOLD TIME: The time that pressure is maintained at the electrodes after the welding current has stopped.
HORIZONTAL WELD: A bead or butt welding process with its linear direction horizontal or inclined at an angle less than 45 degrees to the horizontal, and the parts welded being vertically or approximately vertically disposed.
HORN: The electrode holding arm of a resistance spot welding machine.
HORN SPACING: In a resistance welding machine, the unobstructed work clearance between horns or platens at right angles to the throat depth. This distance is measured with the horns parallel and horizontal at the end of the downstroke.
HOT SHORT: A condition that occurs when a metal is heated to that point, prior to melting, where all strength is lost but the shape is still maintained.
HYDROGEN BRAZING: A method of furnace brazing in a hydrogen atmosphere.
HYDROMATIC WELDING: See PRESSURE CONTROLLED WELDING.
HYGROSCOPIC: Readily absorbing and retaining moisture.
IMPACT TEST: A test in which one or more blows are suddenly applied to a specimen. The results are usually expressed in terms of energy absorbed or number of blows of a given intensity required to break the specimen.
IMPREGNATED-TAPE METAL-ARC WELDING: An arc welding process in which fusion is produced by heating with an electric arc between a metal electrode and the work. Shielding is obtained from decomposition of impregnated tape wrapped around the electrode as it is fed to the arc. Pressure is not used, and filler metal is obtained from the electrode.
INDUCTION BRAZING: A process in which bonding is produced by the heat obtained from the resistance of the work to the flow of induced electric current and by using a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metals. The filler metal is distributed in the joint by capillary attraction.
INDUCTION WELDING: A process in which fusion is produced by heat obtained from resistance of the work to the flow of induced electric current, with or without the application of pressure.
INERT GAS: A gas that does not normally combine chemically with the base metal or filler metal.
INTERPASS TEMPERATURE: In a multipass weld, the lowest temperature of the deposited weld metal before the next pass is started.
J – M
JOINT: The portion of a structure in which separate base metal parts are joined.
JOINT PENETRATION: The maximum depth a groove weld extends from its face into a joint, exclusive of reinforcement.
KERF: The space from which metal has been removed by a cutting process.
LAP JOINT: A joint between two overlapping members.
LAYER: A stratum of weld metal, consisting of one or more weld beads.
LEG OF A FILLET WELD: The distance from the root of the joint to the toe of the fillet weld.
LIQUIDUS: The lowest temperature at which a metal or an alloy is completely liquid.
LOCAL PREHEATNG: Preheating a specific portion of a structure.
LOCAL STRESS RELIEVING: Stress relieving heat treatment of a specific portion of a structure.
MANIFOLD: A multiple header for connecting several cylinders to one or more torch supply lines.
MARTENSITE: Martensite is a microconstituent or structure in quenched steel characterized by an acicular or needle-like pattern on the surface of polish. It has the maximum hardness of any of the structures resulting from the decomposition products of austenite.
MASH SEAM WELDING: A seam weld made in a lap joint in which the thickness at the lap is reduced to approximately the thickness of one of the lapped joints by applying pressure while the metal is in a plastic state.
MELTING POINT: The temperature at which a metal begins to liquefy.
MELTING RANGE: The temperature range between solidus and liquidus.
MELTING RATE: The weight or length of electrode melted in a unit of time.
METAL-ARC CUTTING: The process of cutting metals by melting with the heat of the metal arc.
METAL-ARC WELDING: An arc welding process in which a metal electrode is held so that the heat of the arc fuses both the electrode and the work to form a weld.
METALLIZING: A method of overlay or metal bonding to repair worn parts.
MIG: Gas metal arc welding. Also called MIG for Metal-Inert-Gas. A gun holds the electrode which is the same as the filler rod. The filler rod is fed from a spool eliminating the need to stop and start. Used primarily for welding aluminum and steel.
MIXING CHAMBER: That part of a welding or cutting torch in which the gases are mixed for combustion.
MULTI-IMPULSE WELDING: The making of spot, projection, and upset welds by more than one impulse of current. When alternating current is used each impulse may consist of a fraction of a cycle or a number of cycles.
MULTIPASS WELDS: When multiple welds are applied to one project.
N – P
NEUTRAL FLAME: A gas flame in which the oxygen and acetylene volumes are balanced and both gases are completely burned.
NICK BREAK TEST: A method for testing the soundness of welds by nicking each end of the weld, then giving the test specimen a sharp hammer blow to break the weld from nick to nick. Visual inspection will show any weld defects.
NONFERROUS: Metals which contain no iron. Aluminum, brass, bronze, copper, lead, nickel, and titanium are nonferrous.
NORMALIZING: Heating iron-base alloys to approximately 100 ºF (38 ºC) above the critical temperature range followed by cooling to below that range in still air at ordinary temperature.
NUGGET: The fused metal zone of a resistance weld.
OFW: Abbreviation for oxy-fuel welding. There are three processes in the Oxy group including oxyacetylene, oxyhydrogen and pressure gas welding.
OPEN CIRCUIT VOLTAGE: The voltage between the terminals of the welding source when no current is flowing in the welding circuit.
OVERHEAD POSITION: The position in which welding is performed from the underside of a joint and the face of the weld is approximately horizontal.
OVERLAP: The protrusion of weld metal beyond the bond at the toe of the weld.
OXIDIZING FLAME: An oxyacetylene flame in which there is an excess of oxygen. The unburned excess tends to oxidize the weld metal.
OXYACETYLENE CUTTING: An oxygen cutting process in which the necessary cutting temperature is maintained by flames obtained from the combustion of acetylene with oxygen.
OXYACETYLENE WELDING: A welding process in which the required temperature is attained by flames obtained from the combustion of acetylene with oxygen.
OXY-ARC CUTTING: An oxygen cutting process in which the necessary cutting temperature is maintained by means of an arc between an electrode and the base metal.
OXY-CITY GAS CUTTING: An oxygen cutting process in which the necessary cutting temperature is maintained by flames obtained from the combustion of city gas with oxygen.
OXYGEN CUTTING: A process of cutting ferrous metals by means of the chemical action of oxygen on elements in the base metal at elevated temperatures.
OXYGEN GOUGING: An application of oxygen cutting in which a chamfer or groove is formed.
OXY-HYDROGEN CUTTING: An oxygen cutting process in which the necessary cutting temperature is maintained by flames obtained from the combustion of city gas with oxygen.
OXY-HYDROGEN WELDING: A gas welding process in which the required welding temperature is attained by flames obtained from the combustion of hydrogen with oxygen.
OXY-NATURAL GAS CUTTING: An oxygen cutting process in which the necessary cutting temperature is maintained by flames obtained by the combustion of natural gas with oxygen.
OXY-PROPANE CUTTING: An oxygen cutting process in which the necessary cutting temperature is maintained by flames obtained from the combustion of propane with oxygen.
PASS: The weld metal deposited in one general progression along the axis of the weld.
PEENING: The mechanical working of metals by means of hammer blows. Peening tends to stretch the surface of the cold metal, thereby relieving contraction stresses.
PENETRANT INSPECTION: A non-destructive testing method that detects surface flaws using either fluorescent or dye penetrants. Fluorescent penetrants glow under black light, while dye penetrants produce bright red indications when drawn to the surface by a developer. The process involves cleaning the surface, applying the penetrant, waiting for it to be absorbed, removing excess penetrant, and applying the developer to reveal any defects.
PERCUSSIVE WELDING: A resistance welding process in which a discharge of electrical energy and the application of high pressure occurs simultaneously, or with the electrical discharge occurring slightly before the application of pressure.
PERLITE: Perlite is the lamellar aggregate of ferrite and iron carbide resulting from the direct transformation of austenite at the lower critical point.
PITCH: Center to center spacing of welds.
PLUG WELD: A weld is made in a hole in one member of a lap joint, joining that member to that portion of the surface of the other member which is exposed through the hole. The walls of the hole may or may not be parallel, and the hole may be partially or completely filled with the weld metal.
POKE WELDING: A spot welding process in which pressure is applied manually to one electrode. The other electrode is clamped to any part of the metal much in the same manner that arc welding is grounded.
POROSITY: The presence of gas pockets or inclusions in welding.
POSITIONS OF WELDING: All welding is accomplished in one of four positions: flat, horizontal, overhead, and vertical. The limiting angles of the various positions depend somewhat as to whether the weld is a fillet or groove weld.
POSTHEATING: The application of heat to an assembly after a welding, brazing, soldering, thermal spraying, or cutting operation.
POSTWELD INTERVAL: In resistance welding, the heat time between the end of weld time, or weld interval, and the start of hold time. During this interval, the weld is subjected to mechanical and heat treatment.
PREHEATING: The application of heat to a base metal prior to a welding or cutting operation.
PRESSURE CONTROLLED WELDING: The making of a number of spot or projection welds in which several electrodes function progressively under the control of a pressure sequencing device.
PRESSURE WELDING: Any welding process or method in which pressure is used to complete the weld.
PREWELD INTERVAL: In spot, projection, and upset welding, the time between the end of squeeze time and the start of weld time or weld interval during which the material is preheated. In flash welding, it is the time during which the material is preheated.
PROCEDURE QUALIFICATION: The demonstration that welds made by a specific procedure can meet prescribed standards.
PROJECTION WELDING: A resistance welding process between two or more surfaces or between the ends of one member and the surface of another. The welds are localized at predetermined points or projections.
PULSATION WELDING: A spot, projection, or seam welding process in which the welding current is interrupted one or more times without the release of pressure or change of location of electrodes.
PUSH WELDING: A technique in welding where the welding gun is pushed forward in the direction of the weld, resulting in better visibility and control over the weld. This technique is commonly used in Gas Metal Arc Welding (GMAW) and is preferred for creating clean, spatter-free welds.
Q – S
QUENCHING: The sudden cooling of heated metal with oil, water, or compressed air.
REACTION STRESS: The residual stress which could not otherwise exist if the members or parts being welded were isolated as free bodies without connection to other parts of the structure.
REDUCING FLAME: See CARBURIZING FLAME.
REGULATOR: A device used to reduce cylinder pressure to a suitable torch working pressure.
REINFORCED WELD: The weld metal built up above the surface of the two abutting sheets or plates in excess of that required for the size of the weld specified.
RESIDUAL STRESS: Stress remaining in a structure or member as a result of thermal and/or mechanical treatment.
RESISITANCE BRAZING: A brazing process in which bonding is produced by the heat obtained from resistance to the flow of electric current in a circuit of which the workpiece is a part, and by using a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metals. The filler metal is distributed in the joint by capillary attraction.
RESISTANCE BUTT WELDING: A group of resistance welding processes in which the weld occurs simultaneously over the entire contact area of the parts being joined.
RESISTANCE SPOT WELDING (RSW): Uses electrical current which is passed through the metal. It does not require a filler rod. The process is easy to automate and requires low heat input.
RESISTANCE WELDING: A group of welding processes in which fusion is produced by heat obtained from resistance to the flow of electric current in a circuit of which the workpiece is a part and by the application of pressure.
REVERSE POLARITY: The arrangement of direct current arc welding leads in which the work is the negative pole and the electrode is the positive pole of the welding arc.
ROCKWELL HARDNESS TEST: In this test a machine measures hardness by determining the depth of penetration of a penetrator into the specimen under certain arbitrary fixed conditions of test. The penetrator may be either a steel ball or a diamond spherocone.
ROOT: See ROOT OF JOINT and ROOT OF WELD.
ROOT CRACK: A crack in the weld or base metal which occurs at the root of a weld.
ROOT EDGE: The edge of a part to be welded which is adjacent to the root.
ROOT FACE: The portion of the prepared edge of a member to be joined by a groove weld which is not beveled or grooved.
ROOT OF JOINT: That portion of a joint to be welded where the members approach closest to each other. In cross section, the root of a joint may be a point, a line, or an area.
ROOT OF WELD: The points, as shown in cross section, at which the bottom of the weld intersects the base metal surfaces.
ROOT OPENING: The separation between the members to be joined at the root of the joint.
ROOT PENETRATION: The depth a groove weld extends into the root of a joint measured on the centerline of the root cross section.
SCARF: The chamfered surface of a joint.
SCARFING: A process for removing defects and checks which develop in the rolling of steel billets by the use of a low velocity oxygen deseaming torch.
SEAL WELD: A weld used primarily to obtain tightness and to prevent leakage.
SEAM WELDING: Welding a lengthwise seam in sheet metal either by abutting or overlapping joints.
SELECTIVE BLOCK SEQUENCE: A block sequence in which successive blocks are completed in a certain order selected to create a predetermined stress pattern.
SERIES WELDING: A resistance welding process in which two or more welds are made simultaneously by a single welding transformer with the total current passing through each weld.
SHEET SEPARATION: In spot, seam, and projection welding, the gap surrounding the weld between faying surfaces, after the joint has been welded.
SHIELDED WELDING: An arc welding process in which protection from the atmosphere is obtained through use of a flux, decomposition of the electrode covering, or an inert gas.
SHOULDER: See ROOT FACE.
SHRINKAGE STRESS: See RESIDUAL STRESS.
SINGLE IMPULSE WELDING: The making of spot, projection, and upset welds by a single impulse of current. When alternating current is used, an impulse may consist of a fraction of a cycle or a number of cycles.
SIZE OF WELD: The size of weld refers to the dimensions of the weld, typically its diameter or width and depth, depending on the type of weld. For fillet welds, the size is often described by the leg length, which is the distance from the joint root to the toe of the weld. For groove welds, the size could refer to the depth of penetration or the thickness of the weld bead. The size of the weld plays a critical role in determining the strength and performance of the welded joint.
SKIP SEQUENCE: See WANDERING SEQUENCE.
SLAG INCLUSION: Non-metallic solid material entrapped in the weld metal or between the weld metal and the base metal.
SLOT WELD: A weld made in an elongated hole in one member of a lap or tee joint joining that member to that portion of the surface of the other member which is exposed through the hole. The hole may be open at one end and may be partially or completely filled with weld metal. (A fillet welded slot should not be construed as conforming to this definition.)
SLUGGING: Adding a separate piece or pieces of material in a joint before or during welding with a resultant welded joint that does not comply with design drawing or specification requirements.
SMAW: Shielded metal (stick) arc welding uses a consumable electrode that has a solid metal rod in the core. The rod and electrode melt down and become part of the weld. The electrode is flux coated to protect the weld from contamination.
SOLDERING: A group of welding processes that produce coalescence of materials by heating them to a suitable temperature and by using a filler metal having a liquidus not exceeding 450 ºC (842 ºF) and below the solidus of the base materials. The filler metal is distributed between the closely fitted surfaces of the joint by capillary action.
SOLIDUS: The highest temperature at which a metal or alloy is completely solid.
SPACER STRIP: A metal strip or bar inserted in the root of a joint prepared for a groove weld to serve as a backing and to maintain the root opening during welding.
SPALL: Small chips or fragments which are sometimes given off by electrodes during the welding operation. This problem is especially common with heavy-coated electrodes.
SPATTER: The metal particles expelled during arc and gas welding do not form a part of the weld.
SPOT WELDING: A resistance welding process in which fusion is produced by the heat obtained from the resistance to the flow of electric current through the workpieces held together under pressure by electrodes. The size and shape of the individually formed welds are limited by the size and contour of the electrodes.
SPRAY TRANSFER: A type of metal transfer in which molten filler metal is propelled axially across the arc in small droplets.
SPRAY WELDING: another term for spray arc welding or GMAW.
STAGGERED INTERMITTENT FILLET WELD: Two lines of intermittent welding on a joint, such as a tee joint, wherein the fillet increments in one line are staggered with respect to those in the other line.
STORED ENERGY WELDING: The making of a weld with electrical energy accumulated electrostatically, electromagnetically, or electrochemically at a relatively low rate and made available at the required welding rate.
STRAIGHT POLARITY: The arrangement of direct current arc welding leads in which the work is the positive pole and the electrode is the negative pole of the welding arc.
STRESS RELIEVING: A process of reducing internal residual stresses in a metal object by heating to a suitable temperature and holding for a proper time at that temperature. This treatment may be applied to relieve stresses induced by casting, quenching, normalizing, machining, cold working, or welding.
STRING BEAD WELDING: A method of metal arc welding on pieces 3/4 in. (19 mm) thick or heavier in which the weld metal is deposited in layers composed of strings of beads applied directly to the face of the bevel.
STUD WELDING: An arc welding process in which fusion is produced by heating with an electric arc drawn between a metal stud, or similar part, and the other workpiece, until the surfaces to be joined are properly heated. They are brought together under pressure.
SUBMERGED ARC WELDING: An arc welding process in which fusion is produced by heating with an electric arc or arcs between a bare metal electrode or electrodes and the work. The welding is shielded by a blanket of granular, fusible material on the work. Pressure is not used. Filler metal is obtained from the electrode, and sometimes from a supplementary welding rod.
SURFACING: The deposition of filler metal on a metal surface to obtain desired properties or dimensions.
T – Z
TACK WELD: A weld made to hold parts of a weldment in proper alignment until the final welds are made.
TEE JOINT: A joint between two members located approximately at right angles to each other in the form of a T.
TEMPER COLORS: The colors which appear on the surface of steel heated at low temperature in an oxidizing atmosphere.
TEMPER TIME: In resistance welding, that part of the postweld interval during which a current suitable for tempering or heat treatment flows. The current can be single or multiple impulse, with varying heat and cool intervals.
TEMPERING: Reheating hardened steel to some temperature below the lower critical temperature, followed by a desired rate of cooling. The object of tempering a steel that has been hardened by quenching is to release stresses set up, to restore some of its ductility, and to develop toughness through the regulation or readjustment of the embrittled structural constituents of the metal. The temperature conditions for tempering may be selected for a given composition of steel to obtain almost any desired combination of properties.
TENSILE STRENGTH: The maximum load per unit of original cross-sectional area sustained by a material during the tension test.
TENSION TEST: A test in which a specimen is broken by applying an increasing load to the two ends. During the test, the elastic properties and the ultimate tensile strength of the material are determined. After rupture, the broken specimen may be measured for elongation and reduction of area.
THERMIT CRUCIBLE: The vessel in which the thermit reaction takes place.
THERMIT MIXTURE: A mixture of metal oxide and finely divided aluminum with the addition of alloying metals as required.
THERMIT MOLD: A mold formed around the parts to be welded to receive the molten metal.
THERMIT REACTION: The chemical reaction between metal oxide and aluminum which produces superheated molten metal and aluminum oxide slag.
THERMIT WELDING: A group of welding processes in which fusion is produced by heating with superheated liquid metal and slag resulting from a chemical reaction between a metal oxide and aluminum, with or without the application of pressure. Filler metal, when used, is obtained from the liquid metal.
THROAT DEPTH: In a resistance welding machine, the distance from the centerline of the electrodes or platens to the nearest point of interference for flatwork or sheets. In a seam welding machine with a universal head, the throat depth is measured with the machine arranged for transverse welding.
THROAT OF FILLET WELD: This term encompasses two measurements. The theoretical throat is the perpendicular distance from the root of the joint to the hypotenuse of the largest inscribable right triangle within the fillet-weld cross-section. The actual throat, on the other hand, refers to the distance from the root of the fillet weld to the center of its face. Both measurements are crucial in determining the strength and quality of the weld.
TIG: TIG is another name for GTAW (gas tungsten arc welding). This process uses a non-consumable tungsten electrode and an air cooled or water cooled torch. The process uses an electrical arc to generate heat, costs more than other processes, but is significantly cleaner.
TOE CRACK: A crack in the base metal occurring at the toe of the weld.
TOE OF THE WELD: The junction between the face of the weld and the base metal.
TORCH: See CUTTING TORCH or WELDING TORCH.
TORCH BRAZING: A brazing process in which bonding is produced by heating with a gas flame and by using a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metal. The filler metal is distributed in the joint of capillary attraction.
TRANSVERSE SEAM WELDING: The making of a seam weld in a direction essentially at right angles to the throat depth of a seam welding machine.
TUNGSTEN ELECTRODE: A non-filler metal electrode used in arc welding or cutting, made principally of tungsten.
UNDERBEAD CRACK: A crack in the heat affected zone not extending to the surface of the base metal.
UNDERCUT: A groove melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal.
UNDERCUTTING: An undesirable crater at the edge of the weld caused by poor weaving technique or excessive welding speed.
UPSET: A localized increase in volume in the region of a weld, resulting from the application of pressure.
UPSET WELDING: A resistance welding process in which fusion is produced simultaneously over the entire area of abutting surfaces, or progressively along a joint, by the heat obtained from resistance to the flow of electric current through the area of contact of those surfaces. Pressure is applied before heating is started and is maintained throughout the heating period.
UPSETTING FORCE: The force exerted at the welding surfaces in flash or upset welding.
VERTICAL POSITION: The position of welding in which the axis of the weld is approximately vertical. In pipe welding, the pipe is in a vertical position and the welding is done in a horizontal position.
WANDERING BLOCK SEQUENCE: A block welding sequence in which successive weld blocks are completed at random after several starting blocks have been completed.
WANDERING SEQUENCE: A longitudinal sequence in which the weld bead increments are deposited at random.
WAX PATTERN: Wax molded around the parts to be welded by a thermit welding process to the form desired for the completed weld.
WEAVE BEAD: A type of weld bead made with transverse oscillation.
WEAVING: A technique of depositing weld metal in which the electrode is oscillated. It is usually accomplished by a semicircular motion of the arc to the right and left of the direction of welding. Weaving serves to increase the width of the deposit, decreases overlap, and assists in slag formation.
WELD: A localized fusion of metals produced by heating to suitable temperatures. Pressure and/or filler metal may or may not be used. The filler metal has a melting point approximately the same or below that of the base metals, but always above 800 ºF (427 ºC).
WELD BEAD: A weld deposit resulting from a pass.
WELD GAUGE: A device designed for checking the shape and size of welds.
WELD METAL: That portion of a weld that has been melted during welding.
WELD SYMBOL: A picture used to indicate the desired type of weld.
WELDABILITY: The capacity of a material to form a strong bond of adherence under pressure or when solidifying from a liquid.
WELDER CERTIFICATION: Certification in writing that a welder has produced welds meeting prescribed standards.
WELDER PERFORMANCE QUALIFICATION: The demonstration of a welder’s ability to produce welds meeting prescribed standards.
a. Electrode lead. The electrical conductor between the source of the arc welding current and the electrode holder.
b. Work lead. The electrical conductor between the source of the arc welding current and the workpiece.
WELDING POSITIONS: There are four welding positions including flat, horizontal, overhead and vertical.
WELDING PRESSURE: The pressure exerted during the welding operation on the parts being welded.
WELDING PROCEDURE: The detailed methods and practices including all joint welding procedures involved in the production of a weldment.
WELDING ROD: Filler metal in wire or rod form, used in gas welding and brazing processes and in those arc welding processes in which the electrode does not provide the filler metal.
WELDING SYMBOL: The assembled symbol consists of the following eight elements, or such of these as are necessary: reference line, arrow, basic weld symbols, dimension and other data, supplementary symbols, finish symbols, tail, specification, process, or other references.
WELDING TECHNIQUE: The details of a manual, machine, or semiautomatic welding operation which, within the limitations of the prescribed joint welding procedure, are controlled by the welder or welding operator.
WELDING TIP: The tip of a gas torch especially adapted to welding.
WELDING TORCH: A device used in gas welding and torch brazing for mixing and controlling the flow of gases.
WELDING TRANSFORMER: A device for providing current of the desired voltage.
WELDMENT: An assembly whose component parts are formed by welding.
WIRE FEED SPEED:
The rate of speed in mn/sec or in./min at which a filler metal is consumed in arc welding or thermal spraying.
WORK LEAD: The electric conductor (cable) between the source of arc welding current and the workpiece.
X-RAY: A radiographic test method used to detect internal defects in a weld
YIELD POINT: The yield point is the load per unit area value at which a marked increase in deformation of the specimen occurs with little or no increase of load; in other words, the yield point is the stress at which a marked increase in strain occurs with little or no increase in stress.