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Welding Technology Glossary of Terms used in Weld Processes

Arc Blow
The deflection of an electric arc from its intended path, caused by the magnetic fields generated by the current. This can lead to instability in the welding process. (See also: twin carbon arc brazing).

Arc Cutting
A set of processes that melts the metal being cut using the heat from an arc formed between an electrode and the base metal. Types include carbon arc cutting, metal arc cutting, gas metal arc cutting, gas tungsten arc cutting, plasma arc cutting, and air carbon arc cutting. Compare with oxygen arc cutting.

Arc Gouging
A variation of arc cutting used to form a bevel or groove in the workpiece.

Arc Oxygen Cutting
Also known as oxygen arc cutting, this involves using oxygen to help cut metal with an electric arc.

Automatic Welding
Welding equipment that performs welding operations without requiring operator adjustments to the controls. This equipment may or may not handle the loading and unloading of the workpiece. (See also: machine welding).

Backfire
A momentary retreat of the flame into the welding or cutting tip, followed by its immediate reappearance or complete extinction.

Back Gouging
The process of removing weld metal and base metal from the opposite side of a partially welded joint to ensure complete penetration when welding from that side.

Backing
A material (base metal, weld metal, carbon, or granular material) placed at the root of a weld joint to support the molten weld metal.

Backing Ring

A ring used as a backing material, typically in pipe welding.

Base Material
The material being welded, brazed, soldered, or cut. This term also includes materials other than metals in specific contexts.

Base Metal
The metal being welded, brazed, soldered, or cut. The term implies that base material can also refer to non-metal materials where applicable.

Braze Welding
A welding process in which a filler metal, melting above 840°F but below the solidus temperature of the base metal, is used. Unlike brazing, the filler metal does not flow into the joint by capillary action.

Brazing
A group of processes that join materials by heating them to a suitable temperature and using a filler metal that melts above 840°F but below the solidus temperature of the base metal. The filler metal is distributed by capillary action into the joint.

Burn-Through Weld
An incorrect term used to describe excessive melt-through or a hole. The correct term is "melt-through."

Capillary Action
The process by which a liquid is drawn into the spaces between closely fitted surfaces of a joint, such as in brazing or soldering.

Additional Terms

Carbon Electrode
A non-filler material electrode used in arc welding or cutting, typically made from carbon or graphite, sometimes coated with copper or other materials.

Cladding
A thick layer (greater than 0.04 in.) applied to a surface for improved corrosion resistance or other properties. (See also: coating, surfacing, and hardfacing).

Coalescence
The process by which materials fuse together during welding or brazing.

Constricted Arc
In plasma arc welding and cutting, this refers to a plasma arc that is shaped by a constricting nozzle orifice.

Constricted Nozzle
A water-cooled copper nozzle that surrounds the electrode and contains the constricting orifice used in plasma arc welding and cutting.

Consumable Insert

A pre-placed filler metal that fully fuses into the root of the joint and becomes part of the weld.

Covered Electrode
A composite filler metal electrode with a core of a bare or metal-cored electrode, covered with a material that provides a slag layer, atmospheric shielding, deoxidation, arc stabilization, or additional metallic elements in the weld.

Crack
A fracture type discontinuity characterized by a sharp tip and a high ratio of length and width to opening displacement.

Crater
A depression at the end of a weld bead or in the molten weld pool.

Crater Crack
A crack located in the crater of a weld bead.

Cutting Torch (Oxyfuel Gas)
A tool that directs a preheating flame from the controlled combustion of fuel to the arc and also guides the plasma and shielding gases during cutting.

Defect
A discontinuity that, by nature or accumulated effect (e.g., crack length), causes a part or product to fail to meet minimum acceptance standards or specifications. A defect is considered a rejectable flaw. (See also: discontinuity and flow).

Defective Weld
A weld that contains one or more defects.

Deposited Metal
Filler metal added during a welding operation to form the weld.

Deposition Efficiency (Arc Welding)
The ratio of the weight of deposited metal to the net weight of filler metal consumed, excluding stubs.

Deposition Rate
The amount of material deposited in a unit of time, typically measured in pounds per hour (lb/h).

Depth of Fusion
The distance to which fusion extends into the base metal or previous pass from the surface of the weld during welding.

Dilution
The change in the chemical composition of the filler metal caused by mixing with the base metal or previously deposited weld metal in the weld bead. It is typically measured as the percentage of base metal or weld metal in the deposited weld bead.

Direct Current Electrode Negative (DCEN)
A welding current polarity where the workpiece is the positive pole and the electrode is the negative pole of the welding arc. (See also: straight polarity).

Direct Current Electrode Positive (DCEP)
A welding current polarity where the workpiece is the negative pole and the electrode is the positive pole of the welding arc. (See also: reverse polarity).

Discontinuity
An interruption in the typical structure of a weldment, such as lack of homogeneity in mechanical, metallurgical, or physical properties. Not every discontinuity is a defect. (See also: defect and flow).

Double-Welded Joint
A joint welded from both sides, often used in arc or oxyfuel gas welding.

Dovetailing (Thermal Spraying)
A surface roughening method involving angular undercutting to interlock the spray deposit.

Drop-Through
An undesirable sagging or irregularity, typically encountered when brazing or welding near the solidus temperature of the base metal, caused by overheating and rapid diffusion or alloying of the filler metal and base metal.

Duty Cycle
The percentage of time during a standard test period (usually 10 minutes) that a power supply can be operated at its rated output without overloading.

Welding Technology Glossary of Terms used in Weld Processes

Edge preparation: The surface prepared on the edge of a member for welding.

Edge weld: A weld in an edge joint.

Effective length of weld: The length of the weld throughout which the correctly proportioned cross-section exists. In a curved weld, it shall be measured along the axis of the weld.

Effective throat: The minimum distance from the root of the weld to its face less any reinforcement. See also joint penetration.

Electrode: A component of the welding circuit through which current is conducted to the arc, molten slag, or base metal. See arc welding electrode, bare electrode, carbon electrode, composite electrode, covered electrode, electrode slag, welding electrode, emissive electrode, flux-cored electrode, lightly coated electrode, metal-cored electrode, metal electrode, resistance welding electrode, stranded

electrode, and tungsten electrode.

Electrode extension (GMAW, FCAW, SAW): The length of the unmelted electrode extending beyond the end of the contact tube during welding.

Electrode holder: A device used for mechanically holding the electrode while conducting current to it.

Face of weld: The exposed surface of a weld on the side from which welding was done.

Face reinforcement: Reinforcement of weld at the side of the joint from which welding was done. See also root reinforcement.

Face shield (eye protection): A device positioned in front of the eyes and a portion of, or all of, the face, whose predominant function is protection of the eyes and face. See also hand shield and helmet.

Feed rate (thermal spraying): The rate at which material passes through the gun in a unit of time. A synonym for spray rate.

Filler metal: The metal to be added in making a welded, brazed, or soldered joint. See electrode, welding filler metal, diffusion aid, solder, and spray deposit.

Filler metal start delay time: The time interval from the beginning of downslope time to the stop of filler metal.

Filler metal stop delay time: The time interval from the beginning of downslope time to the stop of filler metal.

Fillet weld: A weld of approximately triangular cross-section joining two surfaces approximately at right angles to each other in a lap joint, T-joint, or corner joint.

Fusion: The melting together of filler metal and base metal (substrate), or of base metal only, which results in coalescence. See depth of fusion.

Fusion welding: Any welding process or method that uses fusion to complete the weld.

Fusion zone: The area of base metal melted as determined on the cross-section of a weld.

Gas shielded arc welding: A general term used to describe gas metal arc welding, gas tungsten arc welding, and flux-cored arc welding when gas shielding is employed.

Gas welding: See preferred term oxyfuel gas welding (OFW).

Groove: An opening or channel in the surface of a part or between two components that provides space to contain a weld.

Groove angle: The total included angle of the groove between parts to be joined by a groove weld.

Groove face: The surface of a member included in the groove.

Groove radius: The radius used to form the shape of a J-or U-groove weld joint.

Groove weld: A weld made in the groove between two members to be joined. The standard types of groove welds are as follows:
• Double-bevel-groove weld, double-flare-bevel-groove weld, double-flare-V-groove weld, double-J-groove weld.
• Double-U-groove weld, double-V-groove weld, single-bevel-groove weld.
• Single-flare-bevel-groove weld, single-flare-V-groove weld, single-J-groove weld.
• Single-U-groove weld, single-V-groove weld, single-groove weld.

Hardfacing: A particular form of surfacing in which a coating or cladding is applied to a substrate for the main purpose of reducing wear or loss of material by abrasion, impact, erosion, galling, and cavitation. See coating, cladding, and surfacing.

Inadequate joint penetration: Joint penetration which is less than that specified.

Inclined position (with restriction ring): The position of a pipe joint in which the axis of the pipe is approximately at an angle of 45° to the horizontal, and a restriction ring is located near the joint. The pipe is not rotated during welding.

Intermittent weld: A weld in which the continuity is broken by recurring unwelded spaces.

Interpass temperatures: In a multiple-pass weld, the temperature (minimum or maximum as specified) of the deposited weld before the next pass is started.

Joint: The junction of members or the edges of members which are to be joined or have been joined.

Joint clearance: The distance between the faying surfaces of a joint. In brazing, this distance is referred to as that which is present before brazing, at the brazing temperature, or after brazing is completed.

Joint design: The joint geometry together with the required dimensions of the welded joint.

Joint efficiency: The ratio of the strength of a joint to the strength of the base metal (expressed in percent).

Joint geometry: The shape and dimensions of a joint in cross-section prior to welding.

Joint penetration: The minimum depth a groove or flange weld extends from its face into a joint, exclusive of reinforcement. Joint penetration may include root penetration. See also complete joint penetration.

Kerf: The width of the cut produced during a cutting process.

Keyhole: A technique of welding in which a concentrated heat source penetrates completely through a workpiece, forming a hole at the lead edge of the molten weld metal. As the heat source progresses, the molten metal fills in behind the hole to form the weld bead.

Lack of fusion: See preferred term incomplete fusion.

Lack of joint penetration: See preferred term inadequate joint penetration.

Metal-cored electrode: A composite filler metal electrode consisting of a metal tube or other hollow configuration containing alloying ingredients. Minor amounts of ingredients providing such functions as arc stabilization and fluxing of oxides may be included. External shielding gas may or may not be used.

Metal electrode: A filler or non-filler metal electrode used in arc welding or cutting that consists of a metal wire or rod that has been manufactured by any method and that is either bare or covered with a suitable covering or coating.

Molten weld pool: The liquid state of a weld prior to solidification as weld metal.

Nozzle: A device that directs shielding media.

Overlap: The protrusion of weld metal beyond the toe, face, or root of the weld. In resistance seam welding, the area in the preceding weld remelted by the succeeding weld.

Overlaying: See preferred term surfacing.

Oxyacetylene cutting (OFC-A): An oxyfuel gas cutting process used to sever metals by means of the chemical reaction of oxygen with the base metal at elevated temperatures. The necessary temperature is maintained by gas flames resulting from the combustion of acetylene with oxygen.

Oxyacetylene welding (OAW): An oxyfuel gas welding process that produces gas welding of metals by heating them with a gas flame or flames obtained from the combustion of acetylene with oxygen. The process may be used with or without the application of pressure and with or without the use of filler metal.

Parent metal: See preferred term base metal.

Partial joint penetration: Joint penetration which is less than complete. See also complete joint penetration.

Pass: See preferred term weld pass.

Peening: The mechanical working of metals using impact blows.

Penetration: See preferred term joint penetration and root penetration.

Pilot arc (plasma arc welding): A low current continuous arc between the electrode and the constricting nozzle to ionize the gas and facilitate the start of the main welding arc.

Plasma: A gas that has been heated to an at least partially ionized condition, enabling it to conduct an electric current.

Plug weld: A circular weld made through a hole in one member of a lap or T-joint fusing that member to the other. The walls of the hole may or may not be parallel, and the hole may be partially or completely filled with weld metal. (A fillet welded hole or a spot weld should not be construed as conforming to this definition.)

Polarity: See direct current electrode negative, direct current electrode positive, straight polarity, and reverse polarity.

Porosity: Cavity-type discontinuities formed by gas entrapment during solidification.

Position of welding: See flat position, horizontal position, horizontal fixed position, horizontal rolled position, inclined position, overhead position, and vertical position.

Post heating: The application of heat to an assembly after a welding, brazing, soldering, thermal spraying, or cutting operation.

Postweld heat treatment: Any heat treatment subsequent to welding.

Preheat: See preferred term preheat temperature.

Preheating: The application of heat to the base metal immediately before welding, brazing, soldering, thermal spraying, or cutting.

Preheat temperature: A specified temperature that the base metal must attain in the welding, brazing, soldering, thermal spraying, or cutting area immediately before these operations are performed.

Procedures: The detailed elements (with prescribed values or ranges of values) of a process or method used to produce a specific result.

Procedure qualification: The demonstration that welds made by specific procedures can meet prescribed standards.

Procedure qualification record (PQR): A document providing the actual welding variables used to produce an acceptable test weld and the results of tests conducted on the weld for the purpose of qualifying a welding procedure specification.

Qualification: See preferred term welder performance qualification and procedure qualification.

Random intermittent welds: Intermittent welds on one or both sides of a joint in which the weld increments are deposited without regard to spacing.

Shrinkage void: A cavity-type discontinuity normally formed by shrinkage during solidification.

Size of weld (groove weld): The joint penetration (depth of bevel plus the root penetration when specified). The size of a groove weld and its effective throat are one and the same.

• Fillet weld: For equal legs fillet welds, the leg lengths of the largest isosceles right triangle which can be inscribed within the fillet weld cross-section. For unequal leg fillet welds, the leg lengths of the largest right triangle which can be inscribed within the fillet weld cross-section. Note: When one angle is greater than 105 degrees, the leg length (size) is of less significance than the effective throat, which is the controlling factor for the strength of a weld.

Slag inclusion: Nonmetallic solid material entrapped in weld metal or between weld metal and base metal.

Slugging: The act of adding a separate piece or pieces of material in a joint before or during welding that results in a welded joint not complying with design, drawing, or specification requirements.

Spacer strip: A metal strip or bar prepared for a groove weld and inserted in the root of a joint to serve as a backing and to maintain root opening during welding. It can also bridge an exceptionally wide gap due to poor fit-up.

Spatter: The metal particles expelled during welding and which do not form a part of the weld.

Start time: The time interval prior to weld time during which arc voltage and current reach a preset value greater or less than welding values.

Surfacing: The deposition of filler metal (material) on a base metal (substrate) to obtain desired properties or dimensions. See also buttering, cladding, coating, and hardfacing.

Tack weld: A weld made to hold parts of a weldment in proper alignment until the final welds are made.

Thermal cutting: A group of cutting processes that melts the metal (material) to be cut. See arc cutting, oxygen cutting, electron beam cutting, and laser beam cutting.

Throat of a fillet weld:

• Theoretical throat: The distance from the beginning of the root of the joint perpendicular to the hypotenuse of the largest right triangle that can be inscribed within the fillet weld cross-section. This dimension is based on the assumption that the root opening is equal to zero.
• Actual throat: The minimum distance minus any reinforcement from the root of the weld to its face. The shortest distance from the root of the weld to its face.

Effective throat:

T-joint: A joint between two members located approximately at right angles to each other in the form of a T.

Toe of crack: A crack in the base metal occurring at the toe of a weld.

Toe of weld: The junction between the face of a weld and the base metal.

Travel angle: The angle that the electrode makes with a reference line perpendicular to the axis of the weld in the plane of the weld axis. See also drag angle and push angle.

Travel angle (pipe): The angle that the electrode makes with a reference line extending from the center of the pipe through the molten weld pool in the plane of the weld axis.

Welding: A localized coalescence of metals or non-metals produced either by heating the materials to suitable temperatures, with or without the application of pressure or by the application of pressure alone and with or without the use of filler material.

Weldability: The capacity of a material to be welded under the fabrication conditions imposed into a specific, suitably designed structure and to perform satisfactorily in the intended service.

Weld crack: A crack in weld metal.

Welder: One who performs a manual or semiautomatic welding operation.

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.

Welding machine: Equipment used to perform the welding operation.

Welding operator: One who operates machine or automatic welding equipment.

Welding position: See flat position, horizontal position, horizontal fixed position, horizontal rolled position, inclined position, overhead position, and vertical position.

Welding procedure: The detailed methods and practices, including all welding procedure specifications, involved in the production of a weldment.

Welding procedure specification (WPS): A document providing in detail the required variables for a specific application to assure repeatability by properly trained welders and welding operators.

Welding process: A materials joining process that produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure or by the application of pressure alone, and with or without the use of filler metal.

Welding rod: A form of filler metal used for welding or brazing which does not conduct the electrical current.

Welding technique: The details of a welding procedure which are controlled by the welder or welding operator.

Weldment: An assembly whose component parts are joined by welding.

Weld metal: That portion of a weld which has been melted during welding.

Weld pass: A single progression of a welding or surfacing operation along a joint, weld deposit, or substrate. The result of a pass is a weld bead, layer, or spray deposit.

Work angle: The angle that the electrode makes with the referenced plane or surface of the base metal in a plane perpendicular to the axis of the weld. See also drag angle and push angle.