Welding Terms & Definitions Part One

This overview (Part One) describes the most commonly used terms in the complex metal joining process through welding.
The welding glossary, according to The American Welding Society (AWS) standard A3.0M/A3.0 includes hundreds of terms, which are presented here in a condensed and adapted form.

A-NUMBER
A designation for ferrous weld metal for procedure qualification based upon chemical composition.

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.

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.

BEVEL ANGLE
The angle formed between the prepared edge of a member and a plane perpendicular to the surface of the member.

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
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.

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

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.

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.

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 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.

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.

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.

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.

GTAW
Welding using an electric arc and non-consumable tungsten electrode in a water cooled torch. Also called TIG or HELLIARC welding.

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.

HAZ
The heat affected zone (HAZ) is an unmelted area of ​​metal whose material properties have changed due to exposure to high temperatures.

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.

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.

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.

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.

The above data, some modified by the owner of wermac.org, comes from the WeldGuru by Jeff Grill

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